At the outbreak of war, Usenko was given command of the 1st Airborne Corps (a division-sized unit) in Southwestern Front. He bravely and skillfully led this unit through July and August, participating in the defense of Kiev. He escaped from the Kiev encirclement with a portion of his troops, and, after a brief assignment as deputy commanding officer of 26th Army in December he was assigned to command of the 2nd Cavalry Corps in Southern Front.