Russia
Russia, with over 3.3 million deaths.
The USSR, suffered numerous millions of deaths, mainly on the eastern front.
According to me the Germans lost the most land post in WW1 because in the end the central powers were defeated by the allied powers which had been consisted of Russia Italy France England USA & Japan.
Brazil is such country.
The Soviet Union: 15 million
Germany
Ukraine
russia
The only country in the world that has never lost a war is Canada.
The Russian Empire
Germany!
Russia
Russia
Russia, with over 3.3 million deaths.
Serbia
The Soviet Union :)