Actually it probably wasn’t long enough. Any exploration of this subject needs to mention that communist parties in western countries were ferociously pacifist before Nazi Germany attacked the USSR and then ferociously pro-war after. In countries like Britain and canada that meant that leftists opposed the war effort from September 1939 to June 1941, and then fanatically supported it afterward. In the USA, they were pacifists until June 1941, and warmongers afterward. While we’re at it, this is the real reason WW2 is remembered as the “good war” in the English-speaking countries. It’s because it’s the only war that the left ever supported.

The history of mankind is one of war, war, and more war. The only thing that brings peace is making your opponents fear the results of making war on you. cf: Current situation in Israel today, Iran, North Korea.