In September 1939 he took part in the campaign in Poland, and was deputy chief of staff of the
7th Army in the
Russo-Finnish War. In August 1940 he was appointed chief of staff of the North Caucasus, from January 1941 to the position of commander of the
Central Asian Military District. With the onset of the
Great Patriotic War, he went on to command the district, and at the same time, from August to October 1941, the 53rd Army, which took part, with Soviet forces from the Transcaucasus, in the
Anglo-Soviet invasion of Iran. From December 1941 to March 1942 he commanded a task force of impressed prisoners gathered from gulags in the Medvezhiegorsky area (1941–1942) on the Karelian front; from March to June 1942, the
32nd Army; from July 1942 to January 1943, the 7th Army; and from January 1943 until the end of the war, the
27th Army. Troops under his command participated in defensive battles in
Karelia, the
Demyansk operations in 1943, the
Battle of Kursk and
Belgorod-Kharkov operation, in the liberation of
Ukraine. During the
Second Jassy–Kishinev Offensive as the 27th Army chief, he effected an attack in the area of the 2nd Ukrainian Front in the
Iași area, breaking through the enemy defense in depth and advancing into the breach of the
6th Panzer Army. After Romania switched sides on 23 August 1944, the army under the command of General Trofimenko advanced rapidly into
Romania, for the first nine days of fighting passed about three hundred kilometers, while cutting apart the rear of the German-Romanian
Army Group South Ukraine; this move took possession of the cities of
Adjud,
Focșani,
Buzău, and
Ploiești. General Trofimenko is thought to be responsible for the great loss of Romanian soldiers, whom he later had in command, during the battle of
Oarba de Mureș, in Romania. By Decree No. 4262 of the
Presidium of the Supreme Soviet of September 13, 1944, for good command of troops in Iași-Kishinev operation and for displaying courage and heroism, Lieutenant-General Sergei G. Trofimenko was awarded the title
Hero of the Soviet Union with the award of the Order of Lenin and medal "Gold Star" .
Post-war service From 1945 to 1946 he was commander of
Tbilisi, from 1946 to 1949,
Belorussian and from 1949 to 1953, the
North Caucasus Military District. In 1949 he graduated from the higher academic courses at the Voroshilov Higher Military Academy He was chosen deputy to the
Supreme Soviet in 1946 and 1953. Trofimenko died on October 16, 1953, in Moscow, and was buried in the
Novodevichy Cemetery. ==Honours and awards==