Born in 1889 in peasant family, during World War I Yegorov graduated a military college in Lyon, France, in 1915.
In December 1917 Yegorov led his Red Guards to Ukraine along with the Antonov's expeditionary task force in fight with counter-revolution in the South Russia.
In March - April 1918 Yegorov headed troops of the Russian Southern Front and later - the Vladikavkaz Military District.
From summer of 1918 to spring of 1919 he was placed in charge of forces in combat area around Vladikavkaz to block off movement of the Denikin's troops.
In summer of 1919, Yegorov led the Poltava task force against the mutinied 6th Ukrainian Soviet Division of Nykyfor Hryhoriv and the Denikin's army.