World War II
World War II lasted between 1939 and 1945. It was fought between the Axis powers (Nazi Germany, Italy, and Japan, amongst others) and the Allies (with Great Britain, the Soviet Union, and the United States at the forefront).
There were disruptions in hockey in Canada and the United States as many hockey players enlisted in the military forces. The hockey leagues across the continent of Europe were shuttered as the war raged.