Why did war break out?

allowing events such as Manchuria to occur, giving Hitler the idea that he could get away with invading Poland and taking the Sudetenland

Stalin believed that appeasement let Hitler get away with

enabled Hitler to attack Poland in a ‘safer’ situation

without it he would have invaded Poland and Russia would have also attacked

along with the ultimatum from Britain and France he would have been fighting a war on both fronts - what he didn’t want

buys Stalin time as he knows if Germany invades, he will be ready