The abbreviation stands for "Red Army". In USSR, it was short for "Workers' and Peasants' Red Army".
The term comes from Russian civil
war, 1917-1922, in which the victorious Reds (bolsheviki/ communists) fought against Whites (monarchists-liberals) and Greens (anarchists).
Red is a well-known political symbol of communism.
Today, most commonly, it refers for the land-
based armed forces; may or
may not include aviation; excludes navy and missile troops.
On 16th of April 1945, The Red
Army began the Berlin Strategic Offensive Operation, which resulted in the unconditional surrender of
German troops on the night of 8 to 9
May 1945.