With the 4th Detachment, he became an aircraft mechanic, fighting on the Eastern, Southeastern, Southern, and Western Fronts of the Russian Civil War.

[3][2] After the Civil War ended, Pumpur remained in the army, serving as an aircraft mechanic with the Commandant's Headquarters of the Central Aerodrome in Moscow from July to December 1921.

In April, he began flight training at the 2nd Military School of Pilots at Borisoglebsk, graduating with the first class of cadets on 26 October.

[3] In July 1925, the squadron was involved in the suppression of a Menshevik and Socialist Revolutionary-backed revolt near the Illinsky Station of the Moscow–Kursk Railway, using its planes to conduct reconnaissance.

After arriving in Spain, the initial group of Soviet pilots, which also included Yevgeny Erlykin, Ivan Kopets, and Anton Kovalevsky in addition to Pumpur, flew their first sorties on the obsolete Spanish Republican Nieuport 52s.

[5] Pumpur led a fighter group of Soviet pilots in the defense of Madrid, flying 250 hours and downing five enemy aircraft.

For his actions he received the title Hero of the Soviet Union on 4 July 1937, and upon his return Pumpur was promoted directly to Komkor from Kombrig, skipping the rank of Komdiv.

Pumpur spent several months at the disposal of the chief of the Air Force, and in December 1938 became head of the flight testing station at Aircraft Plant No.

[2] Just before the beginning of Operation Barbarossa, the German invasion of the Soviet Union, in June 1941, Pumpur's downfall began.