Spain, Sweden, Norway, Denmark, Netherlands, Albania, Switzerland, and Luxembourg
The United States remained neutral in the beginning of WW2 as they did at the beginning of WW1.
Never, Uruguay remained neutral during the whole conflict.
It was Germany
Serbia and austria-Hungary
Several countries and groups did not participate in World War I. Notably, many nations in Central and South America remained neutral throughout the conflict, including Brazil and Argentina. Additionally, countries like Spain, Sweden, and Norway maintained neutrality. Furthermore, some indigenous groups and populations within combatant countries were also not directly involved in the fighting.
Sweden Norway
The United States remained neutral in the beginning of WW2 as they did at the beginning of WW1.
Pretty sure Switzerland remained neutral.
Never, Uruguay remained neutral during the whole conflict.
BritainFranceRussiaItalyU.S
No. Japan remained a monarchy after WW1.
Portugal was an Allie country, making it one of the countries that toke side for the Entente Powers along side with UK, France and others.
The US remained neutral. It declared war in 1917, three years into the war.
It was Germany
Japan and china were the two countries who remained isolated during the age of exploration.
The two African countries that remained independent are Liberia and Ethiopia.
England and Portugal remained undefeated by Napoleon.