The 'Battle of Garfagnana', known to the Germans as 'Wintergewitter' (ii), was a successful Axis offensive against US forces on the western sector of the 'Gotisch-Linie' in the Tuscan northern sector of the Apennine mountains near Massa and Lucca (26/28 December 1944).

Late in December 1944, General Kurt von Tippelskirch’s 14^th Army, using a mixed Italian and German force of some eight infantry battalions, launched a limited offensive against the left wing of Lieutenant General Lucian K. Truscott’s US 5^th Army in the Serchio river valley in front of Lucca with the limited objective of pinning units which might otherwise be switched to the central front. Anticipating an operation of this sort, the Allies had ordered the rapid redeployment of two brigades of Major General D. Russell’s Indian 8^th Division across the Apennine mountains to reinforce Major General Edward M. Almond’s US 92^nd Division. By the time the Indian brigades arrived, the Germans and Italians had broken through to capture Barga and to rout the US division. Reports from captured US soldiers indicated that they had intended to retreat to Lucca and beyond, but decisive action by Russell stabilised the situation. With their objective achieved, the German and Italian force broke off the attack and withdrew. Barga was recaptured one week later, and the front on the western end of the 'Gotisch-Linie' then remained nearly stable until a time late in March 1945.

Benito Mussolini and his minister of national defence, Maresciallo d’Italia Rodolfo Graziani, wanted to create for their revived Fascist state, the Repubblica Sociale Italiana (Italian Social Republic) an Italian army independent of German control. Furthermore, they wished some of the newly created Italian divisions to participate in a major offensive against the Allies in the Italian peninsula. Thus they planned an offensive in the Garfagnana area by two of their new divisions (Generale di Divisione Mario Carloni’s 4a Divisione alpina 'Monterosa' and Generale di Brigata Amilcare Farina’s 3a Divisione fanteria di marina 'San Marco') together with one German division (and possibly one German motorised division), with 40,000 men and air support: their final objective was to have been the retaking of Lucca, Pisa and Livorno in Tuscany. The Italians lacked the required weapons, tanks and warplanes, however, and moreover only the 4a Divisione alpina 'Monterosa' was ready for offensive operations by December 1944.

As a result, therefore, the Germans created their own offensive, 'Wintergewitter' (ii) under the leadership of Generalleutnant Otto Fretter-Pico, of smaller scope and with more limited objectives: just 9,100 men, most of them Italian, attacked in Garfagnana a small area of the 'Gotisch-Linie' that had been lost, aiming to drive the US forces back some 16 miles (25 km) and thereby serve to reduce the Allied pressure in the Rimini area at the other end of the 'Gotisch-Linie'.

Meanwhile, units of Almond’s US 92^nd Division moved to the Garfagnana sector in November, and advanced along the Serchio river valley against light resistance. However, an attempt to capture Castelnuovo di Garfagnana did not succeed. After this, US patrol activity continued until the second half of December.

On 21 December, Graziani and Carloni visited the battalions of the 4a Divisione alpina 'Monterosa' in the Garfagnana to complete preparations for the offensive. After the German 'Wacht am Rhein' on the Western Front in the middle of December, Allied intelligence had considered the possibility of a similar Axis operation in northern Italy. They had come to he conclusion that the most likely objective would be the western coastal sector of the Italian front and, as a result, the Indian 19^th and 21^st Brigades of the Indian 8^th Division were ordered from the central Apennine sector to reinforce the 92^nd Division on the US 5^th Army’s left flank in front of Lucca. The Indian 19^th Brigade arrived on 26 December and was ordered by the commander of US IV Corps, Major General Willis D. Crittenberger, to take position some 4 miles (6.4 km) behind the 92^nd Division. The Indian 21^st Brigade arrived two days later. As further insurance Truscott, the 5^th Army commander, placed two regiments from the US 85^th Division, under Major General John B. Coulter, under Crittenberger’s command and moved additional artillery into range.

On 26 December, several Italian elements, including four battalions of the 4a Divisione alpina 'Monterosa' and 3a Divisione fanteria di marina 'San Marco', launched 'Wintergewitter' (ii) together with three German battalions. A total of 9,100 Axis troops, two-thirds of them Italian, with 100 pieces of artillery pieces but no armour, attacked 18,000 Allied troops with 140 batteries of artillery and 120 tanks, as well as support from 160 Republic P-47 Thunderbolt single-engined fighter-bombers of Brigadier General Benjamin W. Chidlaw’s US XXII Tactical Air Command. The surprise factor was fundamental in the Axis attack, together with a cloudy winter front which, it was hoped, would prevent Allied aircraft from flying. P-47 warplanes of the XXII Tactical Air Command were in the air throughout the day on 26 December, but continued to fly scheduled missions in north-eastern Italy until the severity of the breakthrough was known, but on the following day the XXII Tactical Air Command revised its mission plans to provide support the 5^th Army front, and this was a key element in dislodging the Axis thrust.

The attack against the 92^nd Division was made in two Italian and one German columns. While Fretter-Pico was the overall commander, Carloni was the operational commander. The Italian and German objective was the recapture of the small towns of Barga, Sommocolonia, Vergemoli, Treppignana, Coreglia, Fornaci di Barga, Promiana, Castelvecchio and Calomini in the area to the north-west of Lucca. The Axis order of battle was one column (toward Vergemoli and Calomini) comprising the Italian Alpini Intra battalion, the headquarters defence company of 1o Reggimento alpino, the divisional reconnaissance group of the 4a Divisione alpina 'Monterosa', two battalions of the 6o Reggimento of the 3a Divisione fanteria di marina 'San Marco'; another column (toward Treppignana and Castelvecchio) comprising the Italian 1o Battaglione 'Brescia' of the 8o Reggimento alpino; and the German 1 and 2/286^th Grenadierregiment; and a third (toward Sommocolonia and Barga) comprising the German Gebirgsjägerbataillone 'Mittenwald' and detachments of the Gebirgsjägerbataillon 'Kesselring'.

Early on 26 December, elements of the two German assault battalions from the third column attacked Sommocolonia, which was garrisoned by elements of Company F of the 2/366^th Regiment supported by partisan elements. Some have stated that the resistance there was tough but quickly overwhelmed. In the morning, 200 men of the Gebirgsjägerbataillon 'Mittenwald' seized the US positions to the south of Sommocolonia at Bebbio and Scarpello held by the 92^nd Reconnaissance Troop, which withdrew to Coreglia. In the meantime, Axis mortars had opened fire along the whole front and the other two columns had started moving forward: the two German grenadier battalions together with the attached company of the 1o Battaglione 'Brescia' attacked successfully in the centre down the Serchio river valley to the east of the river. To the west of the river, the other companies of the 1o Battaglione 'Brescia' overcame a weak initial resistance, but their opponents were already falling back and the attackers advanced to Fornaci almost without opposition. Fornaci itself fell quickly, although the two German battalions were heavily criticised for their slow movement and lack of aggression. The first column faced more vigorous opposition on the right of the front, however. The elements of the 3a Divisione fanteria di marina 'San Marco' seized the village of Molazzano without difficulty and pushed the defenders back, but the regimental headquarters company suffered losses and could not take the village of Brucciano. The Gruppo 'Cadelo' of the 4a Divisione alpina 'Monterosa', supported by the Battaglione 'Intra', which made small diversionary attacks, occupied Calomini, but the Vergemoli garrison, comprising the 370^th Regiment and some partisan groups, could not be dislodged. Under threat of encirclement and being cut off it eventually withdrew, leaving in place a partisan group as a covering party.

By 27 December the limited offensive was over. In the morning, the German assault troops entered Pian di Coreglia, their final objective, and Italian patrols went forward as far as the village of Calavorno, reporting that the US forces were still in full retreat. The other columns had also reached their objective, and an entire Allied division had been routed. More than 250 prisoners were taken together with many weapons and much food and equipment. By the late afternoon of 27 December the Axis main offensive had ended, although on the following day there were small territorial consolidations, in what had been a success with a penetration of more than 15.5 miles (25 km) into the Allies lines.

As troops of the 92^nd Division streamed back, they were instructed to take up positions on the left flank of the Indian positions. All Allied troops forming the defence were placed under command of Russell, commander of the Indian 8^th Division. However, the Axis objectives were short of the Indian line and so the Axis attack was not pressed forward. By late afternoon on 27 December, all objectives having been attained, the offensive ended and by the following day the Axis troops were pulling back towards their start lines in a withdrawal completed by 30 December. The Indian 8^th Division performed a bloodless advance simply following on the Axis retreat and no fighting took place. The Germans and Italians had withdrawn from conquered territory and on 8 January 1945 the Indian troops were withdrawn into reserve. The 4a Divisione alpina 'Monterosa' maintained its new advanced line, 1.25 miles (2 km) to the south of the positions they had held on 25 December, until March 1945.

All the objectives of the Axis offensive had been attained: the US 5^th Army was tactically tripped out; Allied reserves were moved to a secondary sector; Italian Social Republican troops' morale was boosted by the success; and the Axis gained a slightly better defensive situation in the north-western Apennines where, indeed, the new front line remained more or less motionless until the April 1945 Axis collapse. Graziani, who had promoted the attack in order to give military importance to the revived Italian fascist state, was extremely satisfied and wanted to continue the offensive. But the air superiority of the Allies stopped any further Axis attack to break south of the 'Gotisch-Linie'. Italian fascist propaganda gave huge importance to the Garfagnana offensive, claiming that it was a small Italian version of the concurrent 'Wacht am Rhein'.