Participants in World War II in the context of "Neutral powers during World War II"

The neutral powers were countries that remained neutral during World War II. Some of these countries had large colonies abroad or had great economic power. Spain had just been through its civil war, which ended on 1 April 1939 (five months prior to the invasion of Poland)—a war that involved several countries that subsequently participated in World War II.

During World War II, the neutral powers took no official side, hoping to avoid attack. However, Portugal, Sweden, and Switzerland all helped the Allies by supplying "voluntary" brigades to the United Kingdom, while Spain avoided the Allies in favor of the Axis, supplying them with its own voluntary brigade, the Blue Division. Ireland generally favoured the Allied side, as with the United States. The United States remained officially neutral until 8 December 1941, a day following the attack by Japan on Pearl Harbor.