The most successful dive-bomber pilot, Hans-Ulrich Rudel, made 2,530 sorties. He contributed to the sinking of the Soviet battleship "Marat" at Kronstadt on 23 September 1941 using bombs. Later, flying a tank-buster Stuka with 20mm cannon, he claimed over 100 Soviet tanks destroyed, mostly at the Battle of Kursk in July 1943. The Ju 87G "Kanonenvogel", equipped with two 37mm BK 3,7 anti-tank guns, as suggested by Rudel, proved to be a lethal weapon in skilled hands. In the Soviet counter-offensive, Operation Kutuzov (July to August 1943), which concluded Kursk, the Luftwaffe claimed 35 tanks destroyed in a single day. Rudel co-wrote a post-war book about his experiences and consulted with the US Air Force.