Приморская армия
During World War II, Petrov participated in the Battle of Odessa, Battle of Sevastopol and was noted for heading the Separate Coastal Army from October 1941 to July 1942 and in November 1943-February 1944, 44th Army in August–October 1942, Black Sea Group of Forces, North Caucasus Front, 33rd Army in 1944, 2nd Belorussian Front, 4th Ukrainian Front, and several other units. In April–June 1945 Petrov was a chief of the 1st Ukrainian Front Staff.