He joined the Russian Social Democratic Labor Party in 1904 and spent five years in jail for revolutionary activities before he was drafted in 1914.

Because of his background, Gai was assigned to the Russo-Ottoman front, where his repeated acts of bravery under fire earned him the rank of stabs-kapitan, the Cross of St. George (3rd and 4th class), and the Order of St. Anna, all awarded by General Nikolai Yudenich.

It was to operate on the extreme right wing of the Soviet advance and turn the flank of the Polish defence lines, thus allowing them to be rolled up by the attacking armies.

[4]: 207 Gai was the People's Commissar of the Army and Navy of the Armenian SSR and later a military history lecturer and researcher in 1922.

He was a professor and the Head of the Department of War History and Military Art in the Zhukovsky Air Force Engineering Academy from 1933 to 1935.

On 3 July 1935, he was arrested and accused of "creating a military-fascist organization in the Red Army" by the Military Collegium of the Supreme Court of the USSR.

[5] On 15 October 1935, Gai was sentenced by the Special Council of the NKVD on charges of involvement in a counter-revolutionary group to 5 years in detention camps.

The passenger river motor ship (riverboat) Komdiv Gai (Комдив Гай, 1963) bears his name.