The '1^st Battle of the Alps', otherwise known as the 'Italian Invasion of France', was the first major Italian military endeavour of World War II and the last major element of the fall France (10/25 June 1940).

Italy’s declaration of war on France and the UK on 10 June widened the scope pf World War II considerably in Africa and the Mediterranean Sea. The goal of Benito Mussolini, the Italian leader, was to remove the British and French domination in the Mediterranean, to reclaim historically Italian territory (Italia irredenta), and to enlarge Italian influence over the Balkans and in North and East Africa. France and the UK had attempted during the 1930s to draw Mussolini away from an alliance with Germany, but the pace of German political and military successes between 1938 and 1940 made Italian intervention on the side of Germany all but inevitable by May 1940.

Italy’s declaration of war war was made during the evening of 10 June to take effect just after midnight. The two sides exchanged air raids on the first day of war, but little transpired on the Alpine front, since on this front both France and Italy had essentially defensive strategies. There was a measure of small-unit skirmishing between patrols, and the French forts of the 'Ligne Alpine' ('little Maginot Line') exchanged fire with their Italian counterparts of the 'Vallo Alpino'. On 17 June, France announced that it would seek an armistice with Germany. During 21 June, on the eve of the signature of a Franco/German armistice, the Italians launched a general offensive along the Alpine front: the main attack was delivered in the northern sector and a secondary advance along the coast. The offensive penetrated a few kilometres into French territory against strong resistance, but stalled before attaining any of its primary objectives except for the coastal town of Menton, situated directly on the Franco/Italian border.

During the evening of 24 June, an armistice was signed at Rome, and came into effect just after midnight on 25 June, at the same time as the France’s armistice with Germany. Italy was allowed to occupy the territory it had captured in the brief fighting, a demilitarised zone was created on the French side of the border, Italian economic control was extended into south-eastern France as far to the west as the Rhône river, and Italy obtained some rights and concessions in certain French colonies. An armistice control commission, the Commissione Italiana d’Armistizio con la Francia, was established in Turin to oversee French compliance.

During the late 1920s, Prime Minister Benito Mussolini spoke with increasing stridency and frequency about imperial expansion, arguing that Italy needed an outlet for its 'surplus population' and that it would therefore be in the best interests of other countries to aid in this expansion. The Italian regime’s immediate desire political 'hegemony in the Mediterranean-Danubian-Balkan region', but with typically grandiose ambition Mussolini had in mind the conquest 'of an empire stretching from the Strait of Gibraltar to the Strait of Hormuz'. Mussolini’s desire for Balkan and Mediterranean hegemony was predicated by the domination of this area by ancient Rome. There were designs for a protectorate over Albania and for the annexation of Dalmatia, as well as economic and military control of Yugoslavia and Greece. The Italian regime also sought to establish protective patron/client relationships with Austria, Hungary, Romania and Bulgaria, all of which lay on the outside edges of Italy’s European sphere of influence. Although it was not among his publicly stated aims, Mussolini also desired to challenge the British and French supremacy in the Mediterranean Sea, which was considered strategically vital as this sea constituted Italy’s sole physical conduit to the Atlantic Ocean in the west and the Indian Ocean in the east.

In 1935, Italy launched the 2^nd Italo-Ethiopian War, and this campaign against a militarily weak opponent suggested optimism for the establishment of an Ethiopian army 'to help conquer' the Anglo-Egyptian Sudan. The war also marked an Italian shift toward a more aggressive foreign policy and also 'exposed [the] vulnerabilities' of the British and French. This in turn established the opportunity which Mussolini needed to begin to realise his imperial objectives. In 1936, the Spanish Civil War broke out, and from its very start Italy played an important role in supporting General Francisco Franco y Bahamonde’s nationalist forces against their republican opponents. The Italian military contribution was so large that it played a decisive role in the nationalist victories which ended the war in 1939. Mussolini had engaged in 'a full-scale external war' in the hope of gaining future Spanish subservience to the Italian Empire, and as a way of placing the country on a war footing and creating a more martial Italian culture. The aftermath of the war in Ethiopia saw a reconciliation of relations between Germany and Italy after years of a previously strained relations, and this resulted in the signature of a treaty of mutual interest in October 1936. Mussolini referred to this treaty as the creation of a Berlin-Rome Axis around which Europe would revolve. The treaty was the result of increasing Italian dependence on German coal following League of Nations sanctions, similar policies between the two countries over the conflict in Spain, and German sympathy toward Italy following European backlash to the 2^nd Ethiopian War. The aftermath of the treaty saw a major increase in ties between Italy and Germany, and Mussolini fell increasingly under Adolf Hitler’s influence from.

In October 1938, in the aftermath of the Munich Agreement that handed the Sudetenland border regions of Czechoslovakia to Germany, Italy demanded concessions from France. These included a free port at Djibouti in French Somaliland, control of the railway linking Addis Ababa, the capital of Ethiopia, and Djibouti, Italian participation in the management of Suez Canal Company, some form of Franco/Italian condominium over French Tunisia, and the preservation of Italian culture on Corsica with no French assimilation of the people. The French refused the demands, believing the true Italian intention was the territorial acquisition of Nice, Corsica, Tunisia and French Somaliland. On 30 November, the Italian foreign minister, Conte Galeazzo Ciano, addressed the Italian chamber of deputies on the 'natural aspirations of the Italian people' and was met with approbatory shouts of 'Nice! Corsica! Savoy! Tunisia! Djibouti! Malta!' Later in the same day, Mussolini addressed the Fascist grand council 'on the subject of what he called the immediate goals of ''Fascist dynamism''.' These goals were Albania; Tunisia; Corsica that was an integral part of France; the Ticino canton of Switzerland; and all 'French territory east of the Var river' including Nice but not Savoy.

Beginning in 1939 Mussolini spoke frequently of his contention that Italy required uncontested access to the world’s oceans and shipping lanes to ensure its national sovereignty. On 4 February of this year, Mussolini addressed the grand council in a closed session and delivered a lengthy speech on international affairs and the goals of his foreign policy. He began by claiming that the freedom of a country is proportional to the strength of its navy. This was followed by 'the familiar lament that Italy was a prisoner in the Mediterranean'. He called Corsica, Tunisia, Malta and Cyprus 'the bars of this prison', and described Gibraltar and Suez as the prison guards. To break British control, her bases on Cyprus, Gibraltar, Malta and in Egypt (controlling the Suez Canal) would have to be neutralized. On 31 March, Mussolini stated that 'Italy will not truly be an independent nation so long as she has Corsica, Bizerta, Malta as the bars of her Mediterranean prison and Gibraltar and Suez as the walls'. Fascist foreign policy took for granted that the democracies (the UK and France) would someday need to be faced down. Through armed conquest Italian North Africa and Italian East Africa, which were separated by the Anglo-Egyptian Sudan, would be linked, and the Mediterranean prison destroyed. Italy would then be in the position to march 'either to the Indian Ocean through the Sudan and Abyssinia, or to the Atlantic by way of French North Africa'.

As early as September 1938, the Italian armed forces had drawn up plans to occupy Albania. On 7 April, Italian forces landed in that country and within three days had occupied the majority of the country. Albania represented a territory Italy could acquire for 'living space to ease its overpopulation' as well as the foothold needed to launch other expansionist conflicts in the Balkans. On 22 May 1939, Italy and Germany signed the Pact of Steel that joined the two countries in a military alliance. The pact was the culmination of German/Italian relations from 1936 and was not defensive in nature. The pact was designed in fact for a 'joint war against France and Britain', although the Italian leadership understood that such a war would not take place for several years: despite the Italian impression, however, the pact made no reference to any such period of peace and the Germans proceeded with their 'Weiss' (i) plan for the invasion and occupation of Poland.

In September 1939, the UK imposed a selective blockade on Italy: for example, German coal, which was shipped out of Rotterdam in the Netherlands, was declared contraband. The Germans promised to keep up shipments by train, over the Alps, and UK offered to supply all of Italy’s needs in exchange for Italian armaments. The Italians could not agree to the latter terms without shattering their alliance with Germany: on 2 February 1940 Mussolini approved a draft contract with the Royal Air Force to provide 400 Caproni aircraft, but cancelled the deal on 8 February. On 1 March, the British announced that they would block all coal exports from Rotterdam to Italy, and Italian coal was one of the issues most discussed in diplomatic circles during the spring of 1940. In April the UK began to enhance the strength of their Mediterranean Fleet so that the blockade could be enforced. Despite French misgivings, the UK rejected concessions to Italy so as not to 'create an impression of weakness'. Germany supplied Italy with about one million tons of coal per month beginning in the spring of 1940, an amount that exceeded Mussolini’s demand of August 1939 that Italy receive six million tons of coal for its first 12 months of war.

On 1 September 1939, Germany invaded Poland, and this 'Weiss' (i) undertaking ended a month later with the total defeat of Poland, whose eastern areas were seized by the Soviets in accord with the Molotov-Ribbentrop agreement of August 1939. There followed a period of inaction, the so-called 'Phoney War', between Germany and the Allied powers. On 10 May 1940, this inactivity ended as Germany began 'Gelb' (or 'Sichelschnitt') against France and the neutral nations of Belgium, the Netherlands and Luxembourg. On 13 May, the Germans fought the Battle of Sedan and crossed the Meuse river, and then quickly encircled the Allies' northern armies. On 27 May, the British and French forces trapped in the north began the 'Dynamo' evacuation from Dunkirk. After the Dunkirk evacuation, the Germans continued their offensive toward Paris in 'Rot' (iii). With more than 60 divisions, compared with the remaining 40 French divisions in the north, the Germans were able to breach the French defensive line along the Somme river by 6 June. Two days later, Parisians could hear distant gunfire. On 9 June, the Germans entered Rouen in upper Normandy. On the following day, the French government abandoned Paris, declaring it an open city, and fled to Bordeaux.

On 23 January 1940, Mussolini remarked that 'even today we could undertake and sustain a…parallel war', having in mind a war with Yugoslavia, since on that day Ciano had met with the dissident Croat leader, Ante Pavelić. A war with Yugoslavia was considered likely by the end of April. On 26 May, Mussolini informed Maresciallo Pietro Badoglio, head of the Italian general staff, and Maresciallo dell’Aria Italo Balbo that he intended to join the German war against the UK and France so to be able to sit at the peace table 'when the world is to be apportioned' in the aftermath of an Axis victory. The two marshals attempted without success to persuade Mussolini that this was unwise as the Italian military was unprepared, divisions were not up to strength, troops lacked equipment, the empire was equally unprepared, and the merchant fleet was scattered across the globe. On 5 June, Mussolini told Badoglio that 'I need only a few thousand dead so that I can sit at the peace conference as a man who has fought.' According to the post-war memoirs of Paul Paillole, in 1940 a captain in the French military intelligence, he was forewarned about the Italian declaration of war on 6 June, when he met Maggiore Navale, an Italian intelligence officer, on the Pont St Louis to negotiate an exchange of captured spies. When Paillole refused Navale’s proposal, the latter warned him that they only had four days to work something out before war would be declared, although nothing much would happen near Menton before 19/20 June.

By the middle of 1940 Germany had revised its earlier preference for Italy as an ally. The pending collapse of France might have been affected by any diversion of German military resources to support a new Alpine front. From a political and economic perspective Italy was useful as a sympathetic neutral and her entry into the war might complicate any peace negotiations with the UK and France.

On 10 June, Ciano informed his ambassadors in London and Paris that a declaration of war would be handed to the British and French ambassadors in Rome at 16.30. When Ciano presented the declaration, the French ambassador, André François-Poncet, was alarmed, while his British counterpart, Percy Loraine, who received the declaration 16.45' 'did not bat an eyelid' according to Ciano. The declaration of war took effect at midnight on the night of 10/11 June. Italy’s other embassies were informed of the declaration shortly before midnight. Commenting on the declaration of war, François-Poncet called it 'a dagger blow to man who has already fallen', and this occasioned US President Franklin D. Roosevelt’s famous remark that 'the hand that held the dagger has struck it into the back of its neighbor'. François-Poncet and the French military attaché in Rome, Général de Corps d’Armée Henri Parisot, declared that France would not fight a 'rushed war', meaning that no offensive against Italy was being contemplated with France’s dwindling military resources.

Late in the day, Mussolini addressed a crowd from the Palazzo Venezia, in Rome. He declared that he had taken the country to war to rectify maritime frontiers. Mussolini’s exact reason for entering the war has been much debated, although the consensus of historians is that it was opportunistic and imperialistic.

On 26 May Général René Henri Olry, commanding the Armée des Alpes, had informed the prefect of Menton, the largest French town on the Franco/Italian border, that the town would be evacuated at night. He gave the order on 3 June and in the course of the following two nights the town was evacuated in 'Mandrin'. On the evening of 10/11 June, after the declaration of war, the French were ordered from their barracks to their defensive positions, and French engineers destroyed the transportation and communication links across the border with Italy using 53 tons of explosives. For the remainder of the short war with Italy, the French took no offensive action.

As early as 14 May, the French ministry of the interior had given orders for the arrest, in the event of war, of Italian citizens known or suspected of being anti-French. Immediately after the declaration of war, the French authorities put up posters in every town near the Italian border ordering all Italian citizens to report to the local police by 15 June. Those who reported were asked to sign a declaration of loyalty that entailed possible future military service. The response was impressive: a majority of Italians reported, and almost all willingly signed the declaration. In Nice, more than 5,000 Italians reported within three days.

In June 1940, only five of the Alpine passes between France and Italy were usable by motor vehicles: these were the Little St Bernard, Mt Cenis, Col de Montgenèvre, Maddalena (Col de Larche) and Col de Tende passes. The only other routes were the coast road and mule trails. Up to September 1939, the Alpine front was defended by Gėnėral d’Armėe Benoît Antoine Marie Roger Besson’s 6^th Army of 550,000 men in 11 divisions, which was more than adequate for the defence of a well-fortified frontier. However, in October the 6^th Army was reduced to the level of a détachement d’armée (army detachment), renamed as the Armée des Alpes and placed under the command of Olry. A plan for a general offensive on the Alpine front, should war with Italy break out, had been created in August 1938 at the insistence of Général d’Armée Gaston Heni Gustave Billotte, the military governor of Paris, and Général d’Armée Maurice Gustave Gamelin, the chief of the national defence staff and soon after this the French commander-in-chief, and in accord with this the Armée des Alpes was deployed for offensive operations in September 1939. However, Olry was instructed not to engage Italian military forces unless thse had fired on French troops.

By December 1939, the Armée des Alpes had been stripped of all its mobile troops, which were shifted to the north for incorporation in the main front against Germany, and Olry’s staff had been much reduced. Olry now had three Alpine divisions, some Alpine battalions, the Alpine fortress demi-brigades, and two demi-brigades of chasseurs alpins, in all a total of some 175,000 to 185,000 men. Only 85,000 of these men were sited on the frontier: 81,000 men in 46 battalions faced Italy, supported by 65 groups of artillery, and 4,500 men faced Switzerland, supported by three groups of artillery. Olry also had B-series reserve divisions: these were second-line troops, most of them reservists in their forties. B-series divisions were a low priority for new equipment and the quality of their training was at best mediocre. The Armée des Alpes had 86 sections d'éclaireurs-skieurs in platoons of 35 to 40 men: these were elite troops trained and equipped for mountain warfare, skiing and mountain climbing.

On 31 May 1940, the Anglo-French Supreme War Council came to the decision that in the event of Italy joining the war air attacks should be launched against industrial and oil-related targets in northern Italy. In this plan, the Royal Air Force was promised the use of two airfields, in the area to the north of Marseille, as advanced bases for bombers flying from the UK. The headquarters of No. 71 Wing arrived at Marseille on 3 June as 'Haddock' Force, which comprised Armstrong-Whitworth Whitley and Vickers Wellington twin-engined bombers of Nos 10, 51, 58, 77, 102 and 149 Squadrons. The French held back part of the Armée de l’Air in case Italy entered the war, as the Zone d’Opérations Aériennes des Alpes (Air Operations Zone of the Alps), with its headquarters at Valence Chabeuil. The Italian army intelligence department, the Servizio Informazioni Militari, overestimated the number of aircraft still available in the Alpine and Mediterranean theatres by 10 June, when many had been withdrawn to face the German invasion. The ZOAA had 70 fighters, 40 bombers and 20 reconnaissance craft, with a further 28 bombers, 38 torpedo bombers and 14 fighters provided by the Aéronavale (naval aviation) and three fighters and 30 other aircraft on Corsica. Italian air reconnaissance had put the number of French aircraft at more than 2,000 and that of British aircraft at more than 620, in the Mediterranean. Italian army intelligence also estimated the strength of the Armée des Alpes at 12 divisions, although at most it had only six by June.

The Armée des Alpes' order of battle on 10 May comprised Général de Brigade René Alphonse Joseph Magnien’s Fortified Sector under the Army including the Defensive Sector of the Rhône; Général de Division Etienne Paul Emile Maroine Beynet’s XIV Corps d’Armée XIX (64ème and 66ème Divisions d’Infanterie de Montagne, the Secteur Fortifié de Savoie and the Secteur Fortifié de la Dauphiné); and Général de Corps d’Armée Alfred Marie Joseph Louis Montange’s XV Corps (2ème Division d’Infanterie Coloniale, 65ème Division d’Infanterie de Montagne and the Secteur Fortifié des Alpes-Maritimes).

During the 1930s, the French had constructed the 'Ligne Maginot' series of fortifications along their border with Germany. This line had been designed to deter a German invasion across the Franco/German border and thus to funnel any German attack into Belgium, where it could then be met by the French army’s best divisions. Thus, any future war would take place outside French territory avoiding a repeat of World War I.

The French had also built another series of fortifications as the 'Ligne Alpine' or 'little Maginot Line'. In contrast to the 'Ligne Maginot' facing the German border, the fortifications in the Alps were not a continuous chain of forts. In the Fortified Sector of the Dauphiné, several passes allowed access through the Alps between Italy and France, and in order to defend these passes, the French had constructed nine artillery and 10 infantry bunkers. In the Secteur Fortifié des Alpes Maritimes, the terrain was less rugged and presented the best possible invasion route for the Italians. In this area, which was 35 miles (56 km) long between the coast and the more impenetrable mountains, the French had built 13 artillery bunkers and 12 infantry forts. Along the border, in front of the above main fortifications, numerous blockhouses and casemates had been constructed. However, by the outbreak of the war some of the positions in the 'Ligne Alpine' had yet to be completed, and the fortifications were in general smaller and weaker than those in the 'Ligne Maginot'.

Italy had a series of similar fortifications in the form of the 'Valle Alpino', which in fact extended right along Italy’s northern border except in those sectors deemed wholly impossible for military operations. By 1939 the section facing France, the Fronte occidentale was based on 460 complete opere (works) similar to the ouvrages of the French defences, with 133 pieces of artillery. As Mussolini prepared to enter the war, construction work continued at breakneck speed along the entire wall, including the section facing Germany. The 'Valle Alpino' was garrisoned by the Guardia alla Frontiera (frontier guard), and the 'Fronte occidentale' was divided into 10 sectors and one autonomous sub-sector. When Italy entered the war, sectors I and V were placed under the command of the XV Corpo d’Armata, sectors II, III and IV under the II Corpo d’Armata and sectors VI, VII, VIII, IX and X under the I Corpo d’Armata.

In the years between the world wars and during 1939, the strength of the Italian military had fluctuated very considerably as a result of successive waves of mobilisation and demobilisation. By the time Italy entered the war, more than 1.5 million men had been mobilised, and the Italian army had created 73 divisions out of this influx of men. However, only 19 of these divisions were complete and fully combat ready, while another 32 were in different stages of establishment and could be used for combat if needed, and the last 22 were unready for battle.

Italy was prepared, in the event of war, for a defensive stance on both the Italian and Yugoslav fronts, or for defence against French aggression, or for an offensive against Yugoslavia while France remained neutral. There was no planning for an offensive against France beyond mobilisation. On the French border, 300,000 men were located in 18 infantry and four alpine divisions. These were deployed defensively, mainly at the entrance to valleys and with their artillery disposed to hit targets inside the border in the event of an invasion. They were not prepared for any assault on the French fortifications, and their deployment was not in fact changed until June 1940. These troops formed the 1a Armata and 4a Armata, which were under the command of Generale d’Armata Umberto di Savoia as the Gruppo d’armate Ovest (Army Group West), whose chief-of-staff was Generale di Corpo d’Armata Emilio Battisti. The 7a Armata was in reserve in the area of Turin, and a further 10 mobile divisions, Generale d’Armata Ettore Bastico’s Esercito del Po (army of the Po), later the 6a Armata were available. However, most of these latter divisions were still in the process of mobilising and were therefore not yet ready for battle.The Gruppe d’armate Overst were 3,000 pieces of artillery and two independent armoured regiments, and after the start of hostilities additional armoured support was provided by the 133a Divisione corazzata 'Littorio', bringing the total number of tanks deployed to about 200. The Divisione corazzata 'Littorio' received 70 examples of the new M11/39 medium tank shortly before the Italian declaration of war.

Despite its numerical superiority, the Italian military was plagued by a large number of problems. During the 1930s, the army had developed an operational doctrine of mobile advances at high speed, backed by heavy artillery support. Starting in 1938, Generale d’Armata Alberto Pariani, the chief of the army general staff, had begun a series of reforms that radically altered the army. By 1940, all Italian divisions had been converted from triangular to binary organisation: rather than having three infantry regiments, the divisions were now based on two regiments, resulting in a total divisional strength of about 7,000 men, and the divisions were therefore smaller than their French counterparts. The number of pieces of artillery in each division had also been reduced, so each division now had only one artillery regiment at a time when their counterparts had three or four. Pariani’s reforms also promoted the concept of the frontal assault over all other tactical doctrine. Moreover, army commanders at the front were forbidden to communicate directly with their aeronautical and naval counterparts, rendering inter-service co-operation almost impossible.

Maresciallo d’Italia Rodolfo Graziani, Pariani’s successor as the chief of the army general staff, had already complained that lack of motor vehicles would render the Italian army incapable of undertaking mobile warfare as had been envisaged in Pariani’s era, let alone at the levels the German military was demonstrating. The issues faced by the Italian army also extended to its weapons and equipment. In overall terms, the Italian troops were poorly equipped and its equipment was inferior to that used by the French. After the Italian invasion of France had started, a circular advised that troops were to be billeted in private homes where possible because of a shortage of tent flies. The vast majority of Italy’s tanks were of the L3/35 tankette type mounting only a machine gun and protected by light armour too thin to prevent the penetration of even machine gun rounds. This tankette was thoroughly obsolete by 1940. It is believed that 70% of engine failure resulted from inadequate driver training. The same issue extended to the artillery arm. Only 246 pieces or artillery, out of the army’s total strength of 7,970 such weapons, were modern with the balance as many as 40 years old and including many guns seized taken as reparations, in 1918, from the Austro-Hungarians.

The Italian air force possessed the third largest fleet of bombers in the world when it entered World War II. A potent symbol of Fascist modernisation, it was the most prestigious of Italy’s service branches, as well as that which had the most recent combat experience as it had been involved in the Spanish Civil War. The 1a Squadra Aerea (1^st Air Fleet) in northern Italy was the most powerful and well-equipped of Italy’s squadre aeree and was responsible for supporting operations on the Alpine front. The Italian anti-aircraft capability was weak: as early as August 1939 Italy had requested from Germany 150 batteries of 88-mm (3.465-mm) anti-aircraft guns, and this request was renewed in March 1940, but refused on 8 June. On 13 June, Mussolini offered to send one Italian armoured division to serve on the German front in France in exchange for 50 anti-aircraft batteries, but the offer was refused.

On 29 May, Mussolini convinced Victor Emanuele III, who was constitutionally the supreme commander of the Italian armed forces, to delegate his authority to Mussolini, and on 4 June Badoglio was already referring to him as supreme commander. On 11 June the king issued a proclamation to all troops, naming Mussolini 'supreme commander of the armed forces operating on all fronts'. This was a mere proclamation and not a royal decree, and thus lacked legal force. Technically, it also restricted Mussolini’s command to forces in combat, but such a distinction was unworkable. On 4 June, Mussolini issued a charter sketching out a new responsibility for the Stato Maggiore Generale (Supreme General Staff), namely to transform his strategic directives into orders for the service chiefs. On 7 June the army high command (Superesercito) ordered the Gruppo d’armate Ovest to remain on the defensive on land and in the air, and two days later the Stato Maggiore del Regio Esercito ordered the army group to strengthen its anti-tank defenses. No attack was planned or ordered for the the day following the declaration of war.

The Gruppo d’armate Ovest had two armies. Generale d’Armata Pietro Pintor’s 1a Armata comprised Generale di Corpo d’Armata Francesco Bettini’s II Corpo d’Armata with the 4a Divisione alpina 'Cuneense', 4a Divisione fanteria 'Livorno', 33a Divisione fanteria 'Acqui' and 36a Divisione fanteria 'Forlì'; Generale di Divisione Mario Arisio’s III Corpo d’Armata with the 3a Divisione fanteria 'Ravenna', 6a Divisione fanteria 'Cuneo' and 1o Gruppo alpino of three Alpini battalions and two mountain artillery groups; and Generale di Divisione Gastone Gambara’s XV Corpo d’Armata with the 5a Divisione fanteria 'Cosseria', 37a Divisione fanteria 'Modena'. 44a Divisione fanteria 'Cremona', and 2o Gruppo alpino with four Alpini battalions, one Camicia Nera (blackshirt) battalion and two mountain artillery groups.

The army’s reserve comprised the 7a Divisione fanteria 'Lupi di Toscana', 16a Divisione fanteria 'Pistoia', 22a Divisione di fanterie 'Cacciatori delle Alpi', 5a Divisione alpina 'Pusteria', 1o Reggimento Bersaglieri, 3o Reggimento corazzato, 13o Reggimento Cavalleggeri di Monferrato and Reggimento Nizza Cavalleria.

The 2o Battaglione of the 63o Reggimento crossed the Little Mont Cenis pass toward the village of Le Planay, where it joined the central column, while the 1o Battaglione crossed the Pas de Bellecombe and augmented the central column at the village of La Villette. The 'Val Cenischia' unit formed the left-hand column, which passed through the Col d'Étache. It was supposed to synchronise its attack on the flank of Modane with the arrival of the central column. The 'Susa' unit formed the right-hand column and crossed the Pas du Chapeau and the Novalesa pass, and then followed the Ribon river toward Bessans, from which it was then to follow the Arc river to Lanslebourg, where it was to link with Colonello Cobianchi’s 3o Battalgione of the 64o Reggimento of the 59a Divisione fanteria 'Cagliari' advancing across the Col de Mont Cenis. The Italian reserve comprised the 11a Divisione fanteria 'Brennero' around Lake Mt Cenis.

The French garrisons these forces faced totalled 4,500 men, backed by two divisions with 60 tanks. The French also had an advanced post at Arcellins, consisting of three blockhouses, which were hidden in fog for much of the time.

The central column began its descent through the Col des Lacs Giaset shortly after 12.00 on 21 June and, as it approached the Ambin river, the column met strong resistance. The 2o Battaglione, coming down the Little Mt Cenis pass, had overcome weak resistance and met the central column. Some small groups were left behind to mop up pockets of resistance while the bulk of the column continued its advance towards Bramans. All of the battalions of the 59a Divisione fanteria 'Cagliari' met around a chapel outside Bramans and, after eliminating the French field fortifications with artillery fire, took the town by the end of the first day. One battalion was diverted to Termignon to link with the Battaglione alpino 'Susa', while the rest proceeded toward Modane. The Battaglione alpino 'Val Cenischia' encountered no resistance as it crossed the Col d'Étache and the Col de Bramanette to emerge in the rear of the Fort de la Balme. The fortifications were taken on 23 June by the 59a Divisione fanteria 'Cagliari', but the forts in front of Modane (St Gobain at Villarodin and the Barrière de l’Esseillon) were much stronger. The Italians attempted to outflank them from the south, and their artillery engaged the forts' guns, but the latter had not been reduced by the time the armistice came into effect, although the advance units of the 59a Divisione fanteria 'Cagliari' were within 3.1 miles (5 km) of Modane.

While the Battaglione alpino 'Susa' had occupied Lanslebourg and moved on to Termignon, the 3o Battaglione of the 64^th Reggimento had been delayed: its route was heavily mined and strewn with anti-infantry and anti-tank obstacles. One battalion of the 231o Reggimento 'Avellino' and one tank battalion of the 11a Divisione fanteria 'Brennero' were sent up to assist it. Two L3 tankettes hit landmines on the narrow cliffside road, halting the entire column and allowing the French artillery to destroy the following tanks. The Italian infantry could advance only very slowly in the face of heavy French fire and in certain cases, having passed well-concealed French machine gun nests, found themselves taking fire from their rear. The Italians managed to surround the powerful Fort de la Turra, but at the time of the armistice it and the advanced post at Arcellins were still firing. The Italian column had not reached Lanslebourg, which had been occupied days earlier by Boccalatte’s force.

Farther to the south, the 1a Armata had been spared responsibility for the main attack, which fell to the 4a Armata in the north, because of the appeals of Pintor, its commander, on 20 June. The southern front of the 1a Armata, in the sector between Monte Grammondo and the coast, was held by the 37a Divisione fanteria da montagna 'Modena' and the 5a Divisione fanteria 'Cosseria', with the 52a Divisione motorizzata 'Torino' of the Esercito del Po in reserve. The army opened its offensive along the whole front on 20 June and in most places was easily repulsed by French artillery.

On 21 June, the units advancing through the Val Roia occupied Fontan. The 5a Divisione fanteria 'Cosseria, advancing along the coast toward Nice, was to be met by Alpini units coming down the valley of the Vésubie river and by marines of the 1o Reggimento 'San Marco' making an amphibious landing behind the French Ouvrage Cap Martin. The amphibious assault had to be called off for logistical reasons including engine failures, the overloading of boats and the roughness of the sea: lacking adequate numbers of dedicated landing craft, the Italian navy had been compelled to commandeer fishing boats and pleasure boats. The Italian navy attempted some landings, but after several craft had grounded, the whole operation was called off. The 5a Divisione fanteria 'Cosseria' was met by a barrage of artillery fire from Cap Martin and the Ouvrage Mont Agel, which destroyed an Italian armoured train. Even so, assisted by thunderstorms and fog, the Italians occupied Les Granges St Paul on 22 June. Mussolini then ordered that the 5a Divisione fanteria 'Cosseria' was to advance regardless of losses.

On the night of 22/23 June, still under the cover of fog, the 5a Divisione fanteria 'Cosseria' bypassed Cap Martin and entered the Garavan quarter of Menton. The bypassed French troops continued to fight, firing at Italian coastal shipping, until the time of the armistice. The fighting in the streets of Menton was fierce. The Italians pushed through the Baousset quarter and took the hill-top Capuchin monastery of Notre Dame de l’Annonciade on 23 June. A planned naval landing at Garavan by the Milizia Volontaria per la Sicurezza Nazionale (Blackshirts) on 24 June had to be called off because of high waves and a full moon. Except for the garrison of the advanced fort of Pont St Louis, the French slowly withdrew from Menton.

On 24 June, Italian infantry reached the plain of Carnolès and was driven off by French artillery fire, and not the Tirailleurs sénégalais as is sometimes stated. Italian aircraft then bombed the French barracks there. That day the fort of Pont St Louis engaged in its last artillery duel with the Italians. No vehicles managed to cross the bridge before the armistice. The capture of Menton was an undeniable but costly Italian success. Mussolini visited the scene of the battle on 1 July and claimed, in a subsequent radio broadcast from Rome, that 'our infantry was supported by an artillery train which came through the tunnel under La Mortola and shelled the strongly held town in which the enemy was maintaining an obstinate resistance'.

Along the 1a Armata's northern front, the 33a Divisione fanteria di montagna 'Acqui', based at the entrance of the Valle Stura di Demonte, comprised six battalions and one 1,300-man MVSN 'legion', and possessed 30 81-mm (3.19-in) mortars, 24 75-mm (2.95-in) 75/13 mountain guns and 12 100-mm (3.94-in) 100/17 modello 16 howitzers. It also had 3,500 mules (for the carriage of its mountain artillery) and horses, 68 motor vehicles, 71 motorcycles and 153 bicycles. The division’s initial deployment was defensive, and some studies had even predicted a French mustard gas attack. On 20 June its orders were to advance up the valley some 37 miles (60 km) into French territory on the only road through the valley. Its radios did not function in the rainy weather, and it soon left its food supply far to the rear, but on 23 June it reached the Maddalena pass, with only one towed 100-mm howitzer, and started to descend the Ubaye river valley into France. Heavy snow and fog slowed the division’s advance, but also prevented the French gunners from adjusting their fire. The 33a Divisione fanteria da montagna 'Acqui' did not reach the French fortifications until late on 24 June, by which time the armistice had been signed. The division lost 32 men dead and 90 men wounded, 198 suffering from frostbite and 15 missing. Because of its lack of artillery in the Ubaye river valley, the division had not fired upon the French forts.

On 17 June, the day after he transmitted a formal request for an armistice to the German government, the French foreign minister, Paul Baudoin, handed to the Papal nuncio Valerio Valeri a note stating that 'The French government, headed by Maréchal Pétain, requests that the Holy See transmit to the Italian government as quickly as possible the note it has also transmitted through the Spanish ambassador to the German government. It also requests that he convey to the Italian government its desire to find together the basis of a lasting peace between the two countries.' That same morning, Mussolini received word from Hitler that France had asked Germany for an armistice, and travelled to meet Hitler at Munich, charging Roatta, Ammiraglio di Squadra Raffaele de Courten and Generale di Brigata Aerea Egisto Perino with drafting Italy’s demands. The final list actually presented to the French were mild, and Italy dropped its claims to the Rhône river valley, Corsica, Tunisia and French Somaliland. According to Roatta, it was Mussolini’s 'sportsmanship' that compelled him not to demand more than he had conquered.

On the evening of 21 June, the Italian ambassador in Berlin, Dino Alfieri, transmitted the German armistice terms to Rome. According to Ciano, 'under these [mild] conditions, Mussolini is not prepared to make territorial demands…and [will] wait for the peace conference to make all our formal demands'. He added that Mussolini wished to delay the meeting with the French in the hopes that Gambara’s forces would take Nice.

At 15.00 on 23 June, the French delegation, headed by Général d’Armée Charles Léon Clément Huntziger, who had signed the armistice with Germany on the previous day, landed in Rome on board one of three German aircraft. The French negotiators were those who had met with the Germans. The first meeting of the two delegations took place at 19.30 at the Villa Incisa all’Olgiata on the Via Cassia and lasted only 25 minutes, during which Roatta announced Italy’s proposed terms. Huntziger requested a recess to confer with his government, and Ciano adjourned the meeting until the next day. During the adjournment, Hitler informed Mussolini that he thought the Italian demands too light, and proposed linking the German and Italian occupation zones. Roatta ultimately convinced Mussolini that it was too late to change the demands.

At 19.15 on 24 June, again in the Villa Incisa and after receiving his government’s permission, Huntziger signed the armistice on behalf of the French, and Badoglio did so for the Italians. Both the German and Italian armistices came into effect at 00.35 on 25 June. Just minutes before the signing, Huntziger had asked Badoglio to strike the clause calling for the repatriation to Italy of political refugees. Badoglio consulted Mussolini, who agreed.

The Franco/Italian armistice established a modest demilitarised zone 31 miles (50 km) deep on the French side of the border, thus eliminating the 'Ligne Alpine' and representing no more than what had been occupied up to the time of the armistice. The Italian occupation zone had an area of 321.25 sq miles (832 km²) and had 28,500 inhabitants, including the 21,700 persons living in Menton. Italy retained the right to interfere in French territory as far to the west as the Rhône river, but did not occupy this area until after the Allied 'Torch' invasion of French North-West Africa in November 1942. In addition, demilitarised zones were established in the French colonies in Africa. Italy was granted the right to use the port of Djibouti in Somaliland together with all of its equipment, along with the French section of the railway linking Addis Ababa and Djibouti. More importantly, the naval bases of Toulon, Bizerte, Ajaccio and Oran were also to be demilitarised within 15 days. Despite the terms of the armistice, the '1^st Battle of the Alps' is often regarded as a French defensive victory.

Reported French army casualties vary between 32 and 40 men killed, between 42 and 121 men wounded, and between 145 and 155 men taken prisoner. The Armée des Alpes also suffered 20 men killed, 84 wounded and 154 taken prisoner in the fighting with the German forces advancing from Lyon. Italian casualties amounted to 631 or 642 men killed, 2,631 men wounded and 616 men reported missing. A further 2,151 men suffered from frostbite during the campaign, but as the official Italian numbers were compiled for a report on 18 July 1940, when many of the fallen still lay under snow, it is likely that most of the Italian missing were in fact dead. Units operating in more difficult terrain had higher ratios of missing to killed, but probably most of the missing had died. For example, the 44o Reggimento of the 36a Divisione fanteria 'Forlì' reported 21 dead, 46 wounded, four frostbitten and at least 296 missing, almost all of whom were captured. The official number of French prisoners of war was 155. All Italian prisoners of war, of whom there is no recorded number but perhaps 1,141, were immediately released, but the armistice negotiators seem to have forgotten the French prisoners, who were sent to the camp at Fonte d’Amore near Sulmona, in which they were later joined by 200 British and 600 Greeks. Although treated in accordance with the laws of war by the Italians, these men probably fell into German hands after Italy’s surrender in September 1943.

The limited Italian demands at the armistice led to speculation in contemporary Italian sources. Roatta believed that Mussolini had curbed his intentions because the military had failed to break the French front line and Mussolini was thus 'demonstrating his sportsmanship'. Alfieri advanced the popular but controversial argument that Mussolini weakened his armistice demands to 'maintain some semblance of a continental balance of power'. It had also been suggested that Mussolini was forced to abandon most of what he wanted at the behest of Hitler, who did not wish to see the arrival of the Italians to be greatly rewarded.

The overall list of Italian war aims remained geographically expansive and a programme published on 26 June set out the acquisition of Nice, Corsica, Tunisia, Malta, southern Switzerland and Cyprus as war aims, as well as the replacement of the UK and France in Egypt, Iraq, Somaliland, the Persian Gulf and southern Arabia.

The historians' consensus is that the Italian military fared poorly during the invasion. On 21 June 1940, Ciano recorded in his diary that Mussolini felt humiliated by the invasion of France as 'our troops have not made a step forward. Even today, they were unable to pass, and stopped in front of the first French strong point that resisted'. Mussolini lambasted the spirit of the Italian people for the failure of the first day of the offensive and, after the armistice, he emphasised his unhappiness as he remarked that it was 'more a political than a military armistice after only 15 days of war – but it gives us a good document in hand'.

The poor showing of the Italians in the Alps was little more than a fiasco with potent morale implications for the Italian generals, who were all noe all too aware of the deficiency of the binary divisional structure. The Italian military had requested aid from the Germans to outflank the French positions, but the initial German attack had been checked and the 'French soldiers of the Alps…did not have to face military defeat as their government had finally succeeded in negotiating an armistice with Italy'. In seeking to explain the Italian deficiency, it has been claimed that the Italian superiority in numbers was betrayed by poor equipment, which was altogether inferior to that of the French, and that 'the stormy Alpine weather was probably the best ally the French had'.

Visiting the Alpine battle sites after the armistice, a German officer remarked that the Blitzkrieg tactics that had served Germany well in northern France would have been difficult in the Alpine terrain, which has been called 'perhaps the most unsuitable of all conceivable theatres of operation'. The attack through the Little St Bernard pass did in fact stall on the first day as a result of a massive snow storm. Italian troops stuck in the snow were easy targets for French snipers, and the winding mule trails provided much opportunity for French ski troops to lay ambushes. The snow also hampered the movement of artillery, food and ammunition to the summits. In some cases, the Italians wore their gas masks because of the difficulty of breathing in the driving snow. The leading troops all too often outran their food supplies and could not be resupplied. On 23 June, for example, the front-line commander of the 4a Divisione alpina 'Cuneense' complained to his superior of the 2a Armata that he was unable to keep in touch with the troops at the front because he could not move his headquarters up the mountain as a result of the weather. Italian field kitchens sometimes lacked the pots and pans to provide warm meals. The Italians also had an insufficient number of engineers and suffered the effects of poor intelligence about French gun emplacements, making the elimination of the forts impossible. In the opinion of Colonello Emilio Faldella, commander of the 3o Reggimento alpino during the invasion of France, the Italian leadership was asking too much of its men.