altitude of , and firing the solid bullets usually used by aircraft Lewis guns was ineffectual: they made small holes causing inconsequential gas leaks. Britain developed new bullets, the Brock containing oxidant potassium chlorate, and the Buckingham filled with phosphorus, which reacted with the chlorate to catch fire and hence ignite the Zeppelin's hydrogen. These had become available by September 1916. The biggest raid to date was launched on 2–3 September, when twelve German Navy and four Army airships set out to bomb London. A combination of rain and snowstorms scattered the airships while they were still over the North Sea. Only one of the naval airships came within seven miles of central London, and both damage and casualties were slight. The newly commissioned Schütte-Lanz SL 11 dropped a few bombs on Hertfordshire while approaching London: it was picked up by searchlights as it bombed Ponders End and at around 02:15 it was intercepted by a B.E.2c flown by Lt. William Leefe Robinson, who fired three 40-round drums of Brocks and Buckingham ammunition into the airship. The third drum started a fire and the airship was quickly enveloped in flames. It fell to the ground near Cuffley, witnessed by the crews of several of the other Zeppelins and many on the ground; there were no survivors. The victory earned Leefe Robinson a Victoria Cross; the pieces of SL 11 were gathered up and sold as souvenirs by the Red Cross to raise money for wounded soldiers. The loss of SL 11 to the new ammunition ended the German Army's enthusiasm for raids on Britain. The German Navy remained aggressive, and another 12-Zeppelin raid was launched on 23–24 September. Eight older airships bombed targets in the Midlands and northeast, while four R-class Zeppelins attacked London. L 30 did not even cross the coast, dropping its bombs at sea. L 31 approached London from the south, dropping a few bombs on the southern suburbs before crossing the Thames and bombing Leyton, killing eight people and injuring 30. L 32 was piloted by Oberleutnant Werner Peterson of the Naval Airship Service, who had only taken command of L 32 in August 1916. L 32 approached from the south, crossing the English Channel close to Dungeness light house, passing Tunbridge Wells at 12:10 and dropping bombs on Sevenoaks and Swanley before crossing over Purfleet. After receiving heavy gunfire and encountering a multitude of anti-aircraft