In 1943 British and American troops invaded German and Italian colonies in Africa to relieve pressure off the Soviet Union and the locals also help beacuase they were treating them like crap and rebels group form.
In June,6,1944 U.S British and Canadian troops invaded Normandy,France and it was not easy in Omaha (not Nebraska) alone 500,000 U.S were killed the rest of the beaches were easy to take bad weather and U.S bomber and destroyers failed to destroy German defenses
In April of 1945 after months of fighting the Soviet Union had reach the capital of Germany Berlin and by this point the German were despirite and were fighting reckless and Hitler was depressed and committed suicide 3 days later Germany surrender
Meanwhile back in the Pacific Theater the US was doing and Island Hopping campaign where they were taking over Small Island leading to Japan and the major Island was Iwo Jima and 50,00 US troops were killed and ended in US victory.
In August of 1945 the leaders of the US,Britain and Soviet Union met in Berlin to decided who would get a piece of Germany and this meeting set up the events in the Cold War.
Even though the two nukes drop on Hiroshima and Nagasaki in Japan they didn't officially surrender until September,3,1945 where they signed a treaty saying that they can no longer use their army and there now under US control.