Initially available to the 'Shingle' planners were tank landing ships sufficient for the landing of only one division but, at Churchill’s insistence, enough were later made available for the landing of two divisions. Allied intelligence believed that there were five or six German divisions in the area, but the 5^th Army intelligence branch severely underestimated the 10^th Army's fighting capacity at the time in the erroneous belief that many of the army’s formations and units were exhausted after the defensive battles they had fought since September.

'Shingle' was initially to have used a single US division landed no later than 15 January 1944, when the required amphibious shipping was to be removed from the Mediterranean in preparation for 'Overlord', the exact date of the landing being determined by the arrival of the 5^th Army at a point some 30 miles (48 km) to the south of the proposed beach-head after breaking through the 'Bernhardt-Linie' and 'Gustav-Linie' positions. The operation was officially cancelled on 18 December, but then various delays postponed the removal of Allied amphibious transport capability to the UK, and the operation was therefore revived but retimed for the later part of January 1944 as Clark’s forces had as yet failed to make the necessary inroads through the 'Bernhardt-Linie' and 'Gustav-Linie' defences.

The Allied plan was finalised on 12 January, three days after the VI Corps had been replaced in the line to the south of Cassino and moved to its embarkation points at Salerno, as part of a five-phase Allied winter offensive against a German army believed to be exhausted and virtually without reinforcements or reserves. 'Shingle' was designed as the third of these phases: the first two were the Allied offensives against the 'Gustav-Linie' and 'Senger-Linie' positions, and the last two the junction with the VI Corps and the destruction of the XIV Panzerkorps.

The Allied forces for 'Shingle' were delivered and supported by a naval element commanded by Rear Admiral Frank J. Lowry of the US Navy, with Lowry’s Force 'X' (Task Force 81) responsible for the transport, landing and support of the US land forces, and Rear Admiral T. H. Troubridge’s Force 'P' for the transport, landing and support of the British land forces. On 21 January TF81, with Lowry on board the headquarters ship Biscayne, departed the Bay of Naples and the landings started early on the next day.

Lowry’s Southern Attack Force comprised five infantry landing ships, 51 tank landing ships, four gun/flak-armed landing craft, 60 infantry landing craft, 32 tank landing craft, two rocket-armed tank landing craft, 23 motor launches and patrol craft/submarine chasers, 10 other craft and the beacon submarine Uproar, and landed the US 3^rd Division. Escort and support were provided by the light cruisers Brooklyn and British Penelope, the US destroyers Plunkett, Gleaves, Niblack, Woolsey, Mayo, Trippe, Ludlow and Edison, a mixed escort destroyer and destroyer escort force comprising the British Croome, Free Greek Themistokles and Kriti, and US Herbert C. Jones and Frederick C. Davis, Free Dutch gunboats Flores and Zoemba, British auxiliary anti-aircraft ship Palomares and 23 US minesweepers.

Troubridge’s Northern Attack Force comprised the headquarters ship Bulolo, three infantry landing ships, three large tank landing ships (Boxer, Bruiser and Buster), 30 tank landing ships, four gun/flak-armed landing craft, 29 infantry landing craft, 17 tank landing craft, one rocket-armed tank landing craft, 17 patrol craft, submarine chasers and motor launches, 13 other craft and the beacon submarine Ultor, and landed Major General W. R. C. Penney’s British 1^st Division. Escort and support were provided the British light cruiser Orion and light anti-aircraft cruiser Spartan, the auxiliary anti-aircraft ship Ulster Queen, the destroyers Jervis, Janus, Laforey, Loyal, Inglefield, Tenacious, Urchin and Kempenfelt, the escort destroyers Beaufort, Brecon, Wilton and Tetcott, and 16 minesweepers.

On the first day of 'Shingle', these Allied naval assets landed 36,034 troops and 3,069 vehicles. The minesweeper Portent was lost on a mine and LCI-20 sank after being hit by a bomb. The anti-aircraft ship Palomares also suffered mine damage. In an air attack on 23 January the destroyers Janus was sunk and and Jervis damaged by Henschel Hs 293 guided weapons. When the first supply convoy arrived on 24 January the 2,702-ton hospital ship St David was sunk by air attack, and the destroyer Plunkett and minesweeper Prevail were damaged. The destroyer Mayo was damaged by an air-launched torpedo. At Naples the 7,176-ton freighter F. A. C. Muhlenberg was damaged by bombs. On 25 January the minesweeper YMS-30 was sunk on a mine and the submarine chaser PC-676 damaged by a bomb. On 26 January LST-422 and LCI-32 were lost on mines, while LST-336 and the freighters John Banward (7,191 tons) and Hilary A. Herbert (7,176 tons) were damaged by fighter-bombers. On 27 January the submarine chaser SC-534 was damaged by bombs. On 29 January the cruiser Spartan and 7,181-ton transport Samuel Huntington succumbed to air attacks by, respectively, a Dornier Do 217K of the III/Kampfgeschwader 100 and Junkers Ju 88 aircraft of the I/Lehrgeschwader 1 armed with guided weapons and bombs.

The initial landing element totalled 40,000 men and more than 5,000 vehicles divided into three attack groups. The northernmost of these, scheduled to land 6 miles (10 km) to the north of Anzio on Peter beach, was Penney’s British 1^st Division (Brigadier E. E. J. Moore’s 2^nd Brigade, Brigadier J. G. James’s 3^rd Brigade and Brigadier A. S. P. Murray’s 24^th Guards Brigade), the 46^th Royal Tank Regiment, and part of Brigadier T. D. L. Churchill’s 2^nd Special Service Brigade (No. 9 Commando and No. 43 [RM] Commando). The division was to land its 2^nd Brigade in the north between Anzio and the Moletta river with the 2^nd Special Service Brigade following it ashore.

The US central group, intended for the attack on the port of Anzio, for which an airborne landing to the north-west of the port by the 504^th Parachute Infantry had been proposed but rejected, was the North-Western Force that was to land on Yellow beach the 6615^th Ranger Force (1^st, 3^rd and 4^th Ranger Battalions and 509^th Parachute Infantry Battalion) with supporting elements. This force was to land the three Ranger battalions in the centre between Anzio and Nettuno, with the 509^th Parachute Infantry Battalion following them ashore.

The southernmost group, intended to land on the coast 3.75 miles (6 km) to the south-east of Anzio on X-Ray beach, was the South-Western Force comprising Truscott’s 3^rd Division (7^th, 15^th and 30^th Infantry), 504^th Parachute Infantry, 751^st Tank Battalion, 601^st Tank Destroyer Battalion and supporting elements. The 3^rd Infantry Division was to land its three infantry regiments in the south between Nettuno and the Mussolini Canal, with the 504^th Parachute Infantry following them ashore.

The rest of the 1^st Division was in floating reserve and follow-on forces, to be committed at Clark’s discretion, were Major General Ernest N. Harmon’s US 1^st Armored Division (less Combat Command B and thus comprising the 1^st Armor and 6^th Armored Infantry) and Major General William W. Eagles�s 45^th Division (157^th, 179^th and 180^th Infantry, and 645^th Tank Destroyer Battalion).

The assault forces were to consolidate a beach-head between the Mussolini Canal and the Moletta via Padiglione. The British would hold the left of the beach-head and then exploit toward Campoleone along the road to Albano, and the Americans would hold the right of the beach-head before exploiting toward Cisterna via Conca. Only after this enlarged beach-head had been secured would Lucas envisage the landing of the 1^st Armored Division and 45^th Division for the assault toward the Alban hills.

The 5^th Army’s initial offensive against the 'Gustav-Linie' defences had begun on 16 January at Monte Cassino. Although the operation failed to capture its target, it partially succeeded in its primary objective: von Vietinghoff-Scheel, commanding the German forces holding the 'Gustav-Linie', called for reinforcement, and Kesselring accordingly transferred Fries’s 29^th Panzergrenadierdivision and Generalleutnant Gerhard Graf von Schwerin-Krosigk’s 90^th Panzergrenadierdivision from Rome. This was what Clark had hoped, for it had been appreciated by the Allies that the Germans could otherwise move forces against the 'Shingle' beach-head more rapidly than the Allies could pour troops into it. Thus the Allies felt that it was vital for the German lines of communication to the south-east of Rome to be interdicted by air power to slow the development of the inevitable German counter-offensive.

Kesselring was fully aware that an amphibious landing might be launched (German contingency plans envisaged such an outflanking operation in places as diverse as Istria, Ravenna, Civitavecchia, Livorno and Viareggio) and had organised a number of extemporised local commands to deal with any such operation, and in the Anzio sector were General Alfred Schlemm and the headquarters of the I Fallschirmkorps.

'Shingle' was committed on 22 January and while resistance had been expected, as at Salerno during 'Avalanche' in September 1943, the initial landings were essentially unopposed with the exception of desultory German air attacks. In themselves, therefore, the 'Shingle' landings were almost the most successful of World War II in any theatre, for there was opposition only from two German battalions and some shore batteries, which were silenced by the guns of the light cruisers and destroyers.

By 24.00 on 22 January the VI Corps had thus landed 36,034 men, 3,069 vehicles and 90% of the corps' assault equipment at the cost of 13 men dead, 97 wounded and 44 missing; about 200 Germans had been taken prisoner. The British 1^st Division penetrated some 1.85 miles (3 km) inland, the Rangers captured the port of Anzio, the 509^th Parachute Battalion took Nettuno, and the 3^rd Division penetrated 3.1 miles (5 km) inland.

It is worth noting that during the first days of the operation, the command of the Italian resistance movement had a meeting with the Allied general headquarters and offered to guide the Allied force in the Alban hills, but the Allied command rejected the offer.

Lucas’s superiors clearly believed that the VI Corps would swiftly undertake offensive action as the primary object of the 'Shingle' landing was to turn the German defences of the 'Gustav-Linie', fall on their exposed rear and, it was hoped, start them into a panic-struck retreat to the north and past Rome. However, Lucas instead concentrated ever more men and matériel into the small beach-head, and strengthened its defences. Churchill was so unhappy with this action that he said 'I had hoped we were hurling a wildcat into the shore, but all we got was a stranded whale.'

It has to be admitted that Lucas found himself in a difficult position and, perhaps swayed by the fact that he lacked confidence in the strategic planning of the operation, he could convince himself that his interpretation of Clark’s orders was reasonable: the two divisions of the VI Corps were, after all, faced by two or three times as many German divisions. On the other side of the coin, it can be argued that Lucas in fact created the worst of two worlds inasmuch as he exposed his forces to risk without imposing any hazard on the Germans.

Kesselring learned of the landings at 03.00 on January 22. Although the landings came as a surprise, Kesselring had made contingency plans to deal with possible landings at all likely locations, as noted above. All Kesselring’s plans relied on each of his divisions having organised a motorised Kampfgruppe rapid-reaction unit for speedy despatch to meet the threat and buy the time needed for Kesselring to bring the rest of the German defences into position. At 05.00 Kesselring triggered the 'Richard' (iii) contingency plan and ordered the Kampfgruppe of Schlemm’s I Fallschirmkorps (Generalmajor Heinrich Trettner’s 4^th Fallschirmjägerdivision from Terni and a number of replacement units of Herr’s LXXVI Panzerkorps including Generalleutnant Paul Conrath’s Panzerdivision 'Hermann Göring' from Frosinone) to hold the roads leading from Anzio and Nettuno to the Alban hills via Campoleone and Cisterna even as the main defence of some 20,000 more men arrived. Moreover, Kesselring requested the Oberkommando der Wehrmacht to despatch reinforcements, and in response the armed forces high command ordered the equivalent of more than three divisions from France, Yugoslavia and Germany (Generalfeldmarschall Gerd von Rundstedt, the Oberbefehlshaber 'West' in France, was instructed to transfer to Kesselring’s command Generalleutnant Hans-Georg Hildebrandt’s 715^th Division, then stationed in the area of Marseille, and Generaloberst Alexander Löhr, the Oberbefehlshaber 'Südost' in the Balkans, was ordered to send to Kesselring’s command Generalleutnant Alexander Bouquin’s 114^th Jägerdivision), and at the same time released to Kesselring another three divisions which had been under the Oberkommando der Wehrmacht’s direct command in Italy. Later in the morning of 22 January, Kesselring ordered von Mackensen’s 14^th Army and von Vietinghoff-Scheel’s 10^th Army to make available additional reinforcements.

The German units in the immediate vicinity had in fact been despatched to reinforce the 'Gustav-Linie' defences just a few days earlier. All available reserves from the southern front or on their way toward this primary defence line were now rushed toward Anzio and Nettuno: these included Generalleutnant Fritz-Hubert Gräser’s 3^rd Panzergrenadierdivision, Generalleutnant Wilhelm Raapke’s 71^st Division and the bulk of the Panzerdivision 'Hermann Göring'.

Kesselring initially considered that his forces would be incapable of mounting a successful defence if the Allies launched a major attack on January 23 or January 24, but by the end of 22 January the lack of any Allied offensive action from the 'Shingle' beach-head had persuaded him that an effective defence could indeed be mounted. Even so, few additional forces arrived to strengthen the defence on 23 January, though the arrival on the evening of 22 January 22 of Schlemm and the headquarters of his I Fallschirmkorps brought greater organisation and purpose to the German defensive preparations, which now included Herr’s LXXVI Panzerkorps (Generalmajor Hans Hecker’s 26^th Panzerdivision, Gräser’s 3^rd Panzergrenadierdivision and Fries’s 29^th Panzergrenadierdivision) from the Sangro river front, and von Mackensen’s 14^th Army headquarters from northern Italy together with Generalleutnant Hellmuth Pfeiffer’s 65^th Division and Generalleutnant Heinrich Greiner’s 362^nd Division. But so severe was the threat to the integrity of the German defences in southern Italy that, as noted above, at Kesselring’s urging the Oberkommando der Wehrmacht had already ordered the Oberbefehlshaber 'West', von Rundstedt, to send Hildebrandt’s 715^th Division from Marseille, and the Oberbefehlshaber 'Südost', Löhr, to hand over Bouquin’s 114^th Jägerdivision from the Balkans.

By 24 January, therefore, the Germans had more than 40,000 men in prepared defensive positions, and the Allies had lost the operational initiative in two days of inaction.

Three days after the landings, the beach-head was surrounded by a defence line comprising three divisions: Trettner’s 4^th Fallschirmjägerdivision in the north-west, Gräser’s 3^rd Panzergrenadierdivision in the centre forward of the Alban hills, and Conrath’s Panzerdivision 'Hermann Göring' in the south-east. von Mackensen’s 14^th Army assumed overall control of the defence on 25 January. Elements of eight German divisions were employed in the defence line around the beach-head, and five more divisions were on their way to the area of Anzio and Nettuno. Kesselring ordered a counterattack on the beach-head for 28 January, but this was postponed to 1 February and started on 3 February as 'Fischfang'.

By 29 January further troop movements, including the arrival of the US 45^th Division and US 1^st Armored Division, had raised the Allied strength in the 'Shingle' beach-head to 69,000 men, 208 tanks and 508 pieces of artillery, while the German total had also risen, in this instance to 71,500 men.

Lucas launched a two-pronged attack on 30 January: the first force was to cut Highway 7 at Cisterna before moving to the east into the Alban hills, and the second was to advance to the north-east up the Via Anziate toward Campoleone. The attack by the 3^rd Division toward Cisterna captured ground up to 3 miles (4.8 km) deep on a front 7 miles (11.25 km) wide, but failed to break through or capture Cisterna. On the right, ahead of the main assault, two Ranger battalions made a daring covert advance towards Cisterna but, as a result of faulty intelligence, they were engaged and cut off after the break of day, and there followed a savage battle with elements of the Panzerdivision 'Hermann Göring'. Rangers began surrendering individually or in small groups prompting others, acting on their own authority, to shoot them. Of the 767 men of the 1^st and 3^rd Ranger Battalions, only six managed to return to the Allied lines, and the other 761 were killed or captured. In the Campoleone thrust, in heavy fighting the British 1^st Division made some ground but failed to take Campoleone and ended the battle in an exposed salient stretching up the Via Anziate.

By a time early in February the 14^th Army numbered some 100,000 German men allocated to Schlemm’s I Fallschirmkorps and Herr’s LXXVI Panzerkorps. By this same time, the Allied forces totalled 76,400 men and included Major General G. W. R. Templer’s recently arrived 56^th Division.

After a making exploratory probes on the Campoleone salient during the afternoon of 3 February, the Germans began their 'Fischfang' first full counterattack at 23.00 with the object of reducing the salient and thereby straightening the front. von Mackensen planned to wear away the narrow salient rather than using a fast-moving thrust to cut it off, and a few hours after the start of 'Fischfang' the stability of the front had been shattered and the fighting for the salient became a series of small unit actions, swaying back and forth through the gullies. By the morning of the 4 February the situation was becoming acute: the 1/Irish Guards had only one cohesive company left and on the opposite side of the salient, the companies of the 6/Gordon Highlanders were beginning to crumble.

Even though the base of the salient was nearly broken, Lucas was able to bolster the defences of the 1^st Division with Brigadier K. C. Davidson’s newly arrived 168^th Brigade of the 56^th Division, allowing the withdrawal of the hard-hit 3^rd Brigade, which had been entrusted with the task of holding the tip of the salient, 2 miles (3.2 km) long and 1,000 yards (915 m) wide, on the road extending to the north of Campoleone. Here, after the German attacks in the early hours of 4 February, the 2/Sherwood Foresters, 1/King’s Shropshire Light Infantry and 1/Duke of Wellington’s Regiment of the 3^rd Brigade had been cut off and were surrounded in the resultant pocket. The three battalions held the line all day despite taking heavy casualties, but were eventually ordered to pull back and from 17.00 made a fighting retreat to the Aprilia Factory under cover of an accurate artillery bombardment.

From 5 to 7 February each side used its heavy artillery concentrations and bombers in efforts to disrupt the other side. At 21.00 on 7 February the Germans renewed their counterattack effort in 'Morgenröte' (ii). Once again, the fighting was severe, the British were compelled to give ground and by 10 February had been pushed out of the salient. Lucas ordered attacks on 11 February to retake the ground which had been lost ground, but the Germans were forewarned by a radio intercept and repelled the Allied attack, which was poorly co-ordinated.

On February 16 the Germans launched a new counterattack as 'Sonnenaufgang' down the line of the Via Anziate, and by 18 February 18, after desperate fighting, the German were attacking the Allies' so-called Final Beach-Head Line, which comprised prepared defences more or less on the line of the original beach-head. Then a counterattack using the VI Corps' reserve halted the German advance, and on 20 February 'Sonnenaufgang' came to an end as each side reached the level of total exhaustion. During 'Sonnenaufgang', the Germans had suffered about 5,400 casualties, and the Allies some 3,500. By this time each side had suffered something in the order of 20,000 casualties since the first landings of 22 January.

Despite the exhausted state of the German troops, Hitler insisted that the 14^th Army should continue to attack and, despite the misgivings of Kesselring and von Mackensen, another assault was mounted on February 29, this time on the front of the LXXVI Panzerkorps around Cisterna. This 'Seitensprung' push achieved little except the infliction of another 2,500 casualties for the 14^th Army.

Throughout this time Churchill had continued to chafe at Lucas’s passive strategy. On 10 February the prime minister wrote to Alexander urging him to exert his authority, and Alexander had visited the beach-head on 14 February to inform Lucas that he wished for a break-out as soon as the situation on the ground made this possible. After his visit, Alexander wrote to General Sir Alan Brooke, the Chief of the Imperial General Staff, to express his disappointment with the headquarters of the VI Corps, which he condemned as negative and lacking in the drive required to get things done, and seemed to have become depressed by events.

At a high-level meeting on 16 February, hosted by Alexander and attended by Clark and General Sir Henry Wilson, the supreme Allied commander in the Mediterranean theatre, the decision was taken to appoint two deputies under Lucas: these were Truscott and the Major General V. Evelegh, commander of the British 6^th Armoured Division. On 22 February, Clark replaced Lucas with Truscott, appointing Lucas deputy commander 5^th Army until such time as a suitable job could be found for him back in the USA.

Each side had come to the realisation that there could be no decisive result in any part of the Italian campaign until the advent of spring, and therefore reverted to a defensive posture based on aggressive patrols and artillery duels even as they worked to improve their fighting capabilities. In anticipation of the resumed campaigning of spring, Kesselring ordered the preparation of a new defence line, the 'Cäsar-Linie', behind the line of beach-head extending from the mouth of the Tiber river just to the south of Rome through Albano, skirting to the south of the Alban hills to Valmontone and thence across Italy to the coast of the Adriatic Sea at Pescara: this was the new line behind which the 14^th Army and 10^th Army, on the German right and left respectively, might withdraw when the need arose.

Meanwhile Truscott, who had been succeeded in command of the US 3^rd Division by Brigadier General John W. O’Daniel, led a staff effort to create a decisive attack as part of the general offensive which Alexander was planning for May and which would include 'Diadem' as a major offensive against the 'Gustav-Linie'. The plan’s objective was to compel Kesselring to commit the full strength of his two armies in Italy and thereby make it impossible for German formations to be redeployed to other theatres, including that in north-western France, on which 'Overlord' was soon to descend. It was also planned, within 'Diadem', to trap the bulk of the 10^th Army between the Allied forces advancing through the 'Gustav-Linie' and the VI Corps thrusting inland from Anzio and Nettuno.

During March and April, the 2/82^nd Waffen Grenadierregiment 'Vendetta', one battalion of the Fusilierbataillon 'Debica' and a third Italian SS battalion of the 1^st Sturmbrigade Italienische Freiwilligen Legion arrived to fight the British and US forces at Anzio and Nettuno, and were dispersed among German battalions. German commanding officers later gave the Italians companies favourable reports. Men of the 2/82^nd Waffen Grenadierregiment, under the command of a former 'Blackshirt' officer, Tenente Colonnello Delgi Oddi, were instrumental in the defeat of a determined effort by the US 3^rd Division to overrun their positions and captured a number of prisoners. This demonstration of courage led on 3 May to the decision of Reichsführer Heinrich Himmler that Italian volunteer units should be redesignated as Waffen-SS units.

In March and early in May, Major General Charles W. Ryder’s US 34^th Division and Major General Fred Walker’s US 36^th Division arrived at Anzio, and Major General P. G. S. Gregson-Ellis’s British 5^th Division replaced the British 56^th Division, the latter after sustaining very heavy losses: one of its battalions, the 7/Oxfordshire and Buckinghamshire Light Infantry of the 167^th Brigade, had been reduced from about 1,000 men to a mere 60. By a time late in May, there were some 150,000 Allied troops in the bridgehead, including five US and two British divisions, to oppose five German divisions. The Germans were well prepared in dug-in defences, but were weak in experienced officers and non-commissioned officers, and by the time of the start of the VI Corps' 'Buffalo' offensive late in May, lacked any reserves as all of these had been sent south to the 'Gustav-Linie' in an attempt to stem 'Diadem'.

Despite the fact that Alexander’s overall plan for 'Diadem' required the VI Corps to strike inland and cut Highway 6, which was the XIV Panzerkorps' natural line of retreat from the 'Gustav-Linie', Clark had asked Truscott to prepare alternatives and to be ready to switch from one to another at 48-hour notice. Of the four scenarios prepared by Truscott, 'Buffalo' mandated an attack through Cisterna into the gap in the hills to cut Highway 6 at Valmontone, while 'Turtle' was based on a main thrust to the left of the Alban hills to take Campoleone and Albano on the way to Rome. On 5 May Alexander selected 'Buffalo' and issued Clark with orders to this effect.

Clark was determined that the VI Corps should strike directly for Rome, however, and argued to Alexander that the VI Corps lacked the strength to intercept and trap the 10^th Army, and rather than making his orders clear, Alexander was conciliatory and gave the impression that a push on Rome was still a possibility if 'Buffalo' encountered problems. On 6 May Clark informed Truscott that Rome was the only important objective and that he was to be ready to execute 'Turtle' as well as 'Buffalo'.

Truscott’s planning for 'Buffalo' was executed meticulously: the British 5^th Division and 1^st Division on the left were to attack along the coast and up the Via Anziate to pin the 4^th Fallschirmjägerdivision, 65^th Division and 3^rd Panzergrenadierdivision as the US 45^th Division, 1^st Armored Division and 3^rd Division would launched the main assault to engage Generalleutnant Heinz Greiner’s 362^nd Division and Hildebrandt’s 715^th Division, and advance on Campoleone, Velletri and Cisterna respectively. On the Allies' far right, Brigadier General Robert T. Frederick’s 1^st Special Service Force would protect the flank of the US assault.