In September of 1915, he assumed command of the 19th Corps Air Detachment but scored no additional victories that year and only 2 more by August of 1916 when he assumed command of the 1st Combat Air Group. In February of 1917, his Corps was ordered to Romania where Kozakov scored eight more victories before being wounded in action on 27 June 1917.
In March, he returned to duty but became deeply depressed by the Russian Civil War and the upcoming withdrawal of British forces from Russia in the summer of 1919.
On the evening of August 1, 1919, ignoring an invitation to a farewell dinner for British pilots, he took off in a Sopwith only to crash to his death a few moments later. Having watched Kozakov pull a loop at low altitude and stall the plane, British pilot, Ira Jones concluded the Russian Ace of Aces "brought about his own death and staged it in the most dramatic manner."
Order of St. George, Order of St. Vladimir, Order of St. Anne, and Order of St. Stanislaus (Russian Empire).
Distinguished Service Order, Military Cross and Distinguished Flying Cross (UK).
Chevalier of the Legion of Honour and Croix de guerre (France)