In the ranks of the 11th Army, he fought on the Southern Front and took part in the occupation of Azerbaijan Democratic Republic in the Soviet-Georgian war of 1921.

On the same year, he was transferred to the Russian Far East, where aged 19, he was appointed commander of a rifle battalion in the 3rd Verkhne-Uda Regiment of the 1st Pacific Division of the People's Revolutionary Army in the Far Eastern Republic.

[2] After the end of the civil war, Krylov remained in the Red Army and continued to serve in the Far East, where he commanded a battalion.

Krylov joined the Communist Party of the Soviet Union in 1927 and graduated from Advanced Training Courses for the Command Staff of the Red Army in August 1928.

In May 1941, he was appointed chief of staff of the Danube Fortified Region on the southern section of the Soviet-Romanian border in the Odessa Military District.

[2] Following the outbreak of Operation Barbarossa in June 1941, Krylov led the fight against Romanian troops who tried unsuccessfully to cross the Soviet border.

When the threat of enemy occupation loomed, the Soviet troops were withdrawn from the border and Krylov became the deputy chief of the coastal army's operational department in July 1941.

During a visit outside the dugout with two others, the Germans fired off mortar rounds, killing one of the men and severely wounding Krylov on 8 January 1942.

[3] Due to his old injury, he was in a Moscow hospital for two months at the end of 1944 and then returned to command of his army units during the East Prussian offensive.

[3] After the victory over Germany, the 5th Army in full strength was transferred to the Far East, where it became part of the 1st Far Eastern Front commanded by Marshal Kirill Meretskov.

[4] For the successful defeat of the opposing enemy groupings in this operation, Krylov was awarded the title Hero of the Soviet Union for the second time.

He was responsible for its founding, which had to be brought into combat readiness within a short time and whose new technology had to be tested in cooperation with the designers.