Guderian's 2nd Panzer Group began its offensive on 22 June by crossing the Bug River and advancing towards the Dnieper. The combined forces of 2nd and 3rd Panzer Groups closed the Minsk pocket, taking 300,000 prisoners before attacking towards Smolensk. Guderian was awarded a Knight's Cross with Oak Leaves on 17 July 1941. Following the conclusion of the Battle of Smolensk, which ended with the encirclement and destruction of the Soviet 16th, 19th and 20th Armies, General Franz Halder, Chief-of-staff of the OKH, argued in favor of the all-out drive toward Moscow. Halder had Guderian fly in to Führer's Headquarters to argue the Army's case for continuing the assault against Moscow. Guderian, who had just recently been vehemently opposed to Hitler's plan for the drive to the south, unexpectedly sided with the dictator. This abrupt change of heart angered both Halder and Field Marshal Fedor von Bock, commander of Army Group Centre, and turned Guderian into somewhat of a pariah amid Army leaders.