The League of Nations’ failure contributed to World War II primarily through its inability to enforce collective security and prevent aggression. The League lacked the authority and military power to enforce its decisions, as seen in its ineffective response to Japan’s invasion of Manchuria in 1931 and Italy’s invasion of Ethiopia in 1935. Major powers like the United States never joined, and others like Germany and Japan withdrew, weakening its influence.

The League’s sanctions were weak and easily bypassed, failing to deter aggressor states. This ineffectiveness emboldened nations like Nazi Germany, leading to policies of appeasement by Britain and France, who sought to avoid conflict by conceding to aggressors’ demands. This emboldened totalitarian regimes in Germany, Italy, and Japan, which pursued expansionist policies unchecked.

The League’s inability to address political and economic instability in Europe allowed these regimes to gain power, increasing tensions and leading to war. The failure of the League underscored the need for a stronger international organization, resulting in the formation of the United Nations after World War II.