The answer is ATOMIC BOMB. World War 1 started in summer 1914 and ended in late 1918. World War 1 weapons includes mustard gas and trench warfare. In August 1914, the Germans were ahead of the pack in terms of grenade development. That first British grenade, the Mark 1 used in 1914, proved highly unpopular with soldiers. Forming a canister with a 16-inch cane handle, it was ignited by removing a safety pin through the top. When thrown, the handle (and attached linen streamers) ensured it landed nose down so that the striker was forced into the detonator. ATOMIC BOMB's neutrons was only discovered in Sept 12, 1932.