The Home Army was the dominant resistance movement in German-occupied Poland during World War II. The Home Army was formed in February 1942 from the earlier Związek Walki Zbrojnej established in the aftermath of the German and Soviet invasions in September 1939. Over the next two years, the Home Army absorbed most of the other Polish partisans and underground forces. Its allegiance was to the Polish government-in-exile in London, and it constituted the armed wing of what came to be known as the Polish Underground State. Estimates of the Home Army's 1944 strength range between 200,000 and 600,000. The latter number made the Home Army not only Poland's largest underground resistance movement but, along with Soviet and Yugoslav partisans, one of Europe's largest World War II underground movements.