As the Battle of Kursk began on July 5, 1943 6th Guards Army was in Voronezh Front, defending the south side of the salient, and 90th Guards was in the second echelon of its Army, dug in behind the swampy basin of the Pena River to defend the most likely German axis of attack towards Oboyan. After the first day's fighting, during which XXXXVIII Panzer Corps and part of II SS Panzer Corps had damaged and forced back the Army's first echelon, Gen. N.F. Vatutin, the Front commander, ordered the 1st Tank Army to support the second echelon. Overnight, 6th Tank Corps buttressed the left and center of the division, while 3rd Mechanized Corps also moved up in support. These reinforcements were important, because the 90th Guards had started the battle understrength, having yielded a rifle battalion and part of its artillery to the first echelon.