The 740 combat airplanes equipping the units at the front on November 11, 1918, were approximately 11% of the total combat aircraft strength of the Allied forces. The 45 squadrons in the Zone of Advance had 767 pilots, 481 observers, and 23 aerial gunners, covering 137 kilometers of front from Pont-à-Mousson to Sedan. They flew more than 35,000 hours over the front lines. The Air Service conducted 150 bombing missions, the longest 160 miles behind German lines, and dropped 138 tons (125 kg) of bombs. Its squadrons had confirmed destruction of 756 German aircraft and 76 German balloons, creating 71 Air Service aces. Rickenbacker finished the war as the leading American ace, with 26 aircraft destroyed. 35 balloon companies also deployed in France, 17 at the front and six en route to the Second Army, and made 1,642 combat ascensions totaling 3,111 hours of observation. 13 photographic sections were assigned to observation squadrons and made 18,000 aerial photographs.