<P> Prior to America 's entry into World War II in December 1941 , individual Americans volunteered to fight against the Axis powers in other nations ' armed forces . Although under American law , it was illegal for United States citizens to join the armed forces of foreign nations and in doing so , they lost their citizenship , many American volunteers changed their nationality to Canadian . However Congress passed a blanket pardon in 1944 . American mercenary Colonel Charles Sweeny living in London began recruiting American citizens to fight as a U.S. volunteer detachment in the French Air force , however France fell before this was implemented . During the Battle of Britain , 11 American pilots flew in the RAF , one of whom was killed , Charles Sweeney 's nephew , also called Charles formed a Home Guard unit from American volunteers living in London . </P>
<P> Prior to America 's entry into World War II in December 1941 , individual Americans volunteered to fight against the Axis powers in other nations ' armed forces . Although under American law , it was illegal for United States citizens to join the armed forces of foreign nations and in doing so , they lost their citizenship , many American volunteers changed their nationality to Canadian . However Congress passed a blanket pardon in 1944 . American mercenary Colonel Charles Sweeny living in London began recruiting American citizens to fight as a U.S. volunteer detachment in the French Air force , however France fell before this was implemented . During the Battle of Britain , 11 American pilots flew in the RAF , one of whom was killed , Charles Sweeney 's nephew , also called Charles formed a Home Guard unit from American volunteers living in London . </P>
when did the us join the allied forces in ww2
when did the us join the allied forces in ww2
December 1941
December 1941