| Unit Name: | 15th Army Group |
| Dates: | 1943–45 |
| Country: | United Kingdom & United States, with numerous allies attached |
| Allegiance: | Allies of World War II |
| Type: | Army group |
| Role: | Army Group Headquarters |
| Size: | 1,200,000 |
| Notable Commanders: | Harold Alexander Mark W. Clark |
The 15th Army Group was an army group in World War II, composed of the British Eighth Army and initially the Seventh United States Army (1943), replaced by the Fifth United States Army (from January 1944), which apart from units from across the British Empire and United States, also had entire units from other allied countries/regions, including: one corps from Free France and one from Poland; one division from Brazil; multiple separate brigades of Italians and Greeks; plus support to, and from, local Italian partisans. It operated in the Italian Campaign from 1943 to 1945.[1]
The 15th Army Group was activated in 1943 in Algiers, North Africa, to plan the invasion of Sicily, codenamed Operation Husky. Its main forces for this job were the Seventh United States Army, under Lieutenant General George Patton, and the British Eighth Army, under General Bernard Montgomery. Following the capture of Sicily, the army group became responsible for the invasion of mainland Italy for which the U.S. Seventh Army was replaced by the U.S. Fifth Army, under Lieutenant General Mark Clark. In January 1944, the army group was re-designated successively Allied forces in Italy and then Allied Central Mediterranean Force.[2]
In March 1944, the army group was renamed Allied Armies in Italy. Throughout this period, the army group was under command of the British General Sir Harold Alexander. By late 1944, the army group had pushed northward through Italy, capturing Rome, and driving the retreating Axis forces into Northern Italy. Despite and due to the rapid advance of the Allied forces in Italy in June–July 1944, after the liberation of Rome, the high allied command in Western Europe decided to take away from the Italian front the French Expeditionary Corps and the U.S. VI Corps, reassigned for landing in the South of France in support of the advance in the north of that country, and to liberate southern France, including the huge port complexes of Marseilles and Toulon, and bring into action the seven divisions of the French 1st Army (1st and 5th armored, 1st, 2nd, 3rd, 4th, and 9th infantry) that had been reequipped in French North Africa by the United States. The gap in the ranks of the U.S. Fifth Army caused by the withdrawal of seven divisions (three US Army, the 3rd, 36th, and 45th infantry divisions; and four French, the 1st, 2nd, 3rd, and 4th divisions) was filled in 1944-45 by five US Army (10th Mountain, 85th, 88th, 91st, and 92nd infantry divisions) and one US-equipped Brazilian Army division (the 1st). Additional replacements and service elements were provided by conversion of the US Army's 2nd Cavalry Division, which had arrived in the theater in 1944.[3]
In order to complicate the Allied ambitions in Italy, between October 1944 and March 1945, the available British forces were also weakened by breaking up the 1st Armoured Division because of a lack of replacements for 8th Army's casualties, and the withdrawal and deployment to Greece of two British infantry divisions (4th and 46th), the British-controlled 4th Indian Division, the British 23rd Armoured Brigade, the British 2nd Parachute Brigade, and the Greek 3rd Mountain Brigade. In addition, the Canadian I Corps and the British 5th Infantry Division were withdrawn and redeployed to northwestern Europe in Operation Goldflake, to make up for British and Canadian losses in France and Belgium in 1944. The British and Canadian divisions that were withdrawn to shore up 21st Army Group took advantage of the ports in southern France liberated by the US 7th and French 1st armies in Operation Dragoon. The new gaps on the Italian front was filled by four Italian "combat groups," each equivalent to a "light" (two brigade) division under the British table of organization and equipment, additional US troops (detached from the forces in France or converted from army-level cavalry and anti-aircraft units) and one additional brigade made up largely of infantry recruited in the British Mandate of Palestine.[4]
In December 1944, Alexander was made Supreme Commander of the Allied Forces Headquarters responsible for all military operations in the Mediterranean theatre and Lieutenant General Mark Clark became the new commander and the army group was renamed 15th Army Group once again.[5] After the definitive break up of the Gothic Line, the Axis forces in Italy were finally defeated in the 15th Army Group's spring offensive, with Axis forces surrendering on 2 May 1945. On 5 July, 15 Army Group was reorganized and redesignated the U.S. Occupational Forces Austria.[6]
Order of Battle for 15th Army Group, August 1944-April 1945