number 36m In 1915, a grenade developed by William Mills, a Birmingham engineer, began to be used by British troops. The bomb had a central spring-loaded firing-pin and and spring-loaded lever locked by a pin. Once the Mills Bomb was in the air, the lever flew up and released the striker, which ignited a four-second time fuse, allowing the thrower to take cover before it exploded. When the grenade went off the cast-iron casing shattered producing a shower of metal fragments
