2 Inch Medium Mortar - The 2-inch Medium Mortar

The 2-inch Medium Mortar

This was designed and manufactured by the Royal Ordnance Factories in early 1915 and introduced along with the 1.57 inch mortar in March 1915. It incorporated what was known of the German prewar Krupp mortar. This was the first design to meet all the requirements, after modifications to simplify manufacture; it fired a good-sized spherical cast-iron bomb of 42 pounds (total projectile weight 51 pounds with stick and fuze), considered the largest practical size for use from trenches, at ranges from 100 to 600 yards using a simple 2-inch tube as the mortar body. The mortar and ammunition could be cheaply manufactured by small unsophisticated "trade" workshops; the bomb was safely detonated by a standard No. 80 "time and percussion" artillery fuze. Drawbacks were that the steel tail was usually projected backwards towards the firer when the bomb detonated, resulting in occasional casualties and the No. 80 fuze was also required by the 18-pounder field guns which were given priority, limiting mortar ammunition supply to the front until early 1916 when a special cheap trench mortar fuze was developed.

The 2-inch mortar served in limited numbers in France in 1915 from March, with early mortars and ammunition made by the Royal Ordnance Factory, with the Vickers 1.57 inch model. Mass production began with an order in August 1915 for 800 mortars from several railway workshops and agricultural machinery makers, together with an order for 675,000 bombs from numerous small firms. Manufacture of the Vickers model which was twice as expensive was ended and it was withdrawn by January 1917.

It fired a spherical cast-iron bomb "the size of a football" painted dirty white filled with Amatol (identified by a painted green band) or Ammonal (identified by a painted pink band) attached to the end of a pipe ("stick"), hence the nicknames "Toffee Apple" and "Plum Pudding". Weights of bombs as delivered without fuzes varied. Light bombs, from 39 lb 14 oz to below 40 lb 10 oz (18.09 to 18.43 kg), were marked with a stenciled "L". Heavy bombs, above 41 lb 10 oz to 42 lb 6 oz (18.43 to 19.22 kg) were marked with a stenciled "Hv". Hence the total fuzed weight with stick of 51 lb is an average.

The 2-inch designation refers to the mortar barrel's bore and the projectile stick inserted into it, not the much-larger bomb itself which remained outside the barrel. It was comparable in explosive power if not range to other 4-inch mortars.

The 2-inch mortar was itself superseded by the Newton 6 inch Mortar from mid-1917 onwards. Some Australian units retained them for projecting smoke screens.