With the defeat of the Polish nation in September 1939, about 80,000 men reformed the Polish Army in Exile in France. A Polish Government in Exile was also formed (Poland being the only country captured by the Germans in which a puppet government was never formed). Two infantry divisions were formed, the Polish 1 Grenadiers Division and 2 Polish Fusiliers Division. In addition, the Independent Polish Highland Brigade served in Norway with the Allies.

With the fall of France, many of the Polish soldiers made their way to the United Kingdom. The Polish personnel were concentrated in South West Scotland, and The Polish Army in Scotland was formed in early August 1940. The G.H.Q. Polish Forces and Polish Ministry of National Defence was formed in London, with the Government in Exile. Initially, the Polish Army comprised two Rifle Brigades and some miscellaneous units. The Headquarters I Polish Corps was formed in late 1941 to administer all the Polish units in the United Kingdom. Recruitment Centre No. 1 was established, and Polish Military Bureaux opened in Edinburgh, Perth and Dundee. A Polish Military Staff College was opened, and training battalions formed.

The formations under command at the beginning of 1942 were the 1 Independent Rifle Brigade, 10 Armoured Cavalry Brigade, 16 Tank Brigade, 1 Independent Parachute Brigade and the Training Brigade. The 10 and 16 Brigades became part of the 1 Polish Armoured Division which formed on 25 February 1942. This formation later served in North West Europe under command of the British 2 Army.

In late 1944, the Corps expanded with the influx of Polish soldiers who had previously served in the German Army. This allowed the formation of an infantry division, which with the 16 Independent Armoured Brigade were the two operational formations in the Corps. The Corps never saw active service during the war, but was deployed to Wilhelmshaven in 1945 to take command of the area, with the 1 Armoured Division and 1 Independent Parachute Brigade under command. The Corps overtook occupation duties until 1947, when the all the Polish formations were disbanded.

Many of the personnel were unable to return to their native Poland which was now under Soviet occupation, so they settled in exile in the United Kingdom and other countries in the West. It is estimated that about 140,000 Polish soldiers and their dependents were absorbed into the United Kingdom from 1946 onwards. The Polish Resettlement Corps was formed in 1946 specifially for this purpose, with several Army camps being taken over to house the Poles. One of the last camps is at Stover, near Newton Abbot in Devon, which is known locally as ‘Little Poland’.