British forces, sent to aid the Greeks, are forced to withdraw to the island of Crete. In mid-May, German paratroopers land on Crete and, after heavy fighting, defeat the British there. Yugoslavia and Greece are partitioned among the victors. Three German army groups advance deep into Soviet territory. Millions of Soviet soldiers are encircled and forced to surrender.
German troops continue to advance to the outskirts of Moscow.
In December 1941, the Soviet Union launches a counteroffensive, forcing a German retreat from Moscow. This time the goals are the oil fields of the Caucasus and the city of Stalingrad on the Volga River. By the beginning of July, German forces cross the Don River and by mid-September reach the suburbs of Stalingrad. The Soviet army command decides to defend the city, no matter what the cost. Soviet forces fight for every street in the city.