The Cold War was a period of tension between the United States and its allies against the Soviet Union and its allies from the 1940s to the early 1990s. They competed for power and influence in subtle ways rather than direct war. Major events like the rise of the Berlin Wall and Cuban Missile Crisis were related to Cold War tensions. The uneasy relationship began as the Allied powers joined with the Soviet Union in WWII but sour relations grew as Germany was divided and the Soviets gained more control over Eastern Europe. Both sides then sought to demonstrate their power through the space race as each tried to one-up the other technologically and scientifically.