Yes Mr. Churchill did fight during World War II, not only on the battlefield, but also with speeches.
Portugal was neutral during World War II so didn't fight anyone.
Great Britain
Probably Russia, then France
Germany.
They didn't fight at all
Winston Churchill was British Prime Minister during World War 2
Hell no
Antarctica.
T.S. Eliot did not fight in the war, but he did serve as a volunteer in the British Army during World War I as a way to contribute to the war effort. He worked as a firefighter during the London Blitz in World War II.
Russia
The nation of Vietnam came into existence in 1975 (on paper in 1976). So are you asking about that Vietnam or the Vietnam War? There was no nation called "Vietnam" during the Vietnam War.