Hand grenade, British, World War I No. 23 Dated 12/16 (December 1916) Maker "LP&S W. INERT. Missing striker, striker spring, filler plug for shoulder, safety pin and ring. A bent nail is replacing the pin. Threaded tip of rifle grenade launching rod is in bottom of base plate. Looks a lot like a No. 36 M Mk. I grenade but is an earlier model. THIS MODEL MAY HAVE A ROD TO BE FIRED BY A RIFLE. The Mills bomb is the popular name for a series of prominent British hand grenades. They were the first modern fragmentation grenades in the world. William Mills, a hand grenade designer from Sunderland, patented, developed and made the "Mills bomb" at the Mills Munition Factory in Birmingham, England, in 1915. The Mills bomb was inspired by an earlier design of the Belgian captain Leon Roland. Roland and Mills were later engaged a patent lawsuit. The Mills bomb was adopted by the British Army as its standard hand grenade in 1915, and designated as the No. 5. The Mills bomb underwent numerous modifications. The No. 23 was a variant of the No. 5 with a rodded base plug which allowed it to be fired from a rifle. This concept evolved further with the No. 36, a variant with a detachable base plate to allow use with a rifle discharger cup. The final variation of the Mills bomb, the No. 36M, was specially designed and waterproofed with shellac for use initially in the hot climate of Mesopotamia in 1917, but remained in production for many years. By 1918 the No. 5 and No. 23 were declared obsolete and the No. 36 (but not the 36M) followed in 1932. The Mills was a classic design; a grooved cast iron "pineapple" with a central striker held by a close hand lever and secured with a pin. According to Mills' notes the casing was grooved to make it easier to grip and not as an aid to fragmentation, and in practice it has been demonstrated that it does not shatter along the segmented lines. The Mills was a defensive grenade: after throwing the user had to take cover immediately. A competent thrower could manage 15 metres (49 feet) with reasonable accuracy, but the grenade could throw lethal fragments farther than this.