On 15 October 1944, Tiger IIs of 503rd Heavy Panzer Battalion played a crucial role during Operation Panzerfaust, supporting Otto Skorzeny's troops in taking the Hungarian capital of Budapest, which ensured that the country remained with the Axis until the end of the war. The 503rd then took part in the Battle of Debrecen. The 503rd remained in the Hungarian theater of operations for 166 days, during which it accounted for at least 121 Soviet tanks, 244 anti-tank guns and artillery pieces, five aircraft and a train. This was set against the loss of 25 Tiger IIs; ten were knocked out by Soviet troops and burned out, two were sent back to Vienna for a factory overhaul, while thirteen were blown up by their crews for various reasons, usually to prevent them from falling into enemy hands. Kurt Knispel, the highest scoring tank ace of all time (162 enemy armoured fighting vehicles destroyed), also served with the 503rd, and was killed in action on 28 April 1945 in his Tiger II.