The _howitzer_ as a weapon for use against the submarine when submerged was almost non-existent at the beginning of 1917, only thirty bomb-throwers, on the lines of trench-mortars, being on order. By April of that year designs for seven different kinds of bomb-throwers and howitzers had been prepared and approved, and orders placed for 1,006 weapons, of which number the first 41 were due for delivery in May. By the end of May the number of bomb-throwers and howitzers on order had been increased to 2,056, of eight different patterns. Over 1,000 of these weapons fired a bomb or shell carrying a burster exceeding 90 lbs. in weight, and with a range varying between 1,200 and 2,600 yards. Later in the war, as we gained experience of the value of this form of attack, heavier bombs were introduced for use in the existing bomb-throwers and howitzers. The howitzer as an anti-submarine weapon was handicapped by the comparatively small weight of the bursting charge of its shell. This applied more particularly to the earlier patterns, and to inflict fatal injury it was necessary to burst the shell in close proximity to the submerged submarine. This weapon, although not very popular at first, soon, however, proved its value, when employed both from patrol craft and from merchant ships. One curious instance occurred on March 28, 1918, of a merchant ship being saved by a 7.5-inch howitzer. A torpedo was seen approaching at a distance of some 600 yards, and it appeared certain to hit the ship. A projectile fired from the howitzer exploded under water close to the torpedo, deflected it from its course, and caused it to come to the surface some 60 yards from the ship; a second projectile caused it to stop, and apparently damaged the torpedo, which when picked up by an escorting vessel was found to be minus its head. Delivery of howitzers commenced in June, 1917, and continued as follows: Total completed, No. of Howitzers including those Date. actually issued. under proof. July 24, 1917 35 48 October 1, 1917 92 167 December 10, 1917 377 422 The slow rate of delivery, in spite of constant pressure, which is shown by these figures gives some idea of the time required to bring new devices into existence. PROJECTILE FOR USE AGAINST SUBMARINES In January, 1917, the Director of Naval Ordnance was requested by the Anti-Submarine Division of the Naval Staff to carry out trials against a target representing the hull of a German submarine, so far as the details were known to us, to ascertain _the most suitable type of projectile_ amongst those then in existence for the attack of submarines by guns of 4.7-inch calibre and below.