Vignette. Some Adventures with Trench Mortars. December 1914-January 1915.

3rd Division. Attack on Wytschaete. December 14th, 1914.

The Composite Company.

On September 7th, the Commander, Royal Engineers, 3rd Division, formed a Composite Company RE by withdrawing suitable tradesmen from the other Field Companies in the Division. Its role was to carry out special or one-off engineering activities within the Division’s area of operations, at that time, the British Sector of the Ypres Salient.

In late November, Sir John French agreed to support a French attack on the Messines Ridge by providing a diversionary attack on the strongly defended village of Wytschaete to prevent the Germans from moving troops to strengthen their defences on the ridge. This attack was to be carried out by the 8th Infantry Brigade, and to support them, the Composite Company manufactured a batch of live and dummy hand grenades and spent several afternoons in late November and early December training parties from the 8th Brigade in the use of hand and rifle grenades.

1st Division Mortars. Sir Dougla Haig’ loan.

At this time the 3rd Division was not in a position to produce trench mortars and general Haig offered to led two of Lieutenant Bateman’s mortars, along with a hundred mortar bombs to support the attack on Wytschaete scheduled for December 14th and in the afternoon of the 13th Sappers from the 26th Field Company RE turned up at the billets of the Composite Company and handed over two trench mortars with their ration of ammunition to Lieutenant Denning.

We do not know how much instruction the Sappers of the 26th Field Company gave on how to use the mortars, but it was not enough for Lieutenant Denning, with his two scratch mortar crews, who had never seen a trench mortar before, spent the rest of the afternoon examining the mortars and their ammunition and working out how to fire them, but were unable to get in a practice shoot as darkness fell before they found somewhere suitable to serve as a firing range.

Having been ordered to have the mortars in position to support the attack of the 8th Infantry Brigade, Lieutenant Denning paraded his men at 3.30 am on the 14th and succeeded in placing the mortars in position just before dawn. Their role was to suppress the German positions in the Petit Bois in front of Wytschaete, from which they could enfilade the infantry attack.

Captain Denning’s Report on the Attack

Denning’s report is probably a fair representation of the effectiveness of the improvised mortars available to the BEF in late 1914 in.[1] He managed to fire off 30 rounds and of these 14 landed on, or near, the enemy positions and were considered effective; there were two premature explosions, one of which destroyed a mortar without casualties among the crews; the other exploded in the air about halfway to the target; and all the remainder were blinds. The range achieved was 50-150 yards, and the effect of firing the mortar was judged as good as, or better than, that of rifle grenades. Lieutenant Denning attributed the 14 blinds to the following: fuse failing to light when the bombs left the gun, seven rounds; wooden plug and detonator falling out during flight, four rounds; the remaining three bounced around on landing, probably knocking out the plug that held the detonator.

Denning had several suggestions for improvements. The gun emplacements were muddy, and the mortars’ stability would be much improved if they were bolted to a heavy wooden platform. Cutting the fuse to the correct length and keeping the exposed end dry in a muddy trench under fire was difficult, and the time taken to assemble the bomb and load the mortar with the propellant charge took too long. When Lieutenant Bateman received the report on the performance of his mortars and ammunition, he was inclined to blame Denning for the misfires because, in the absence of anything else, he had sealed the mortar bombs, just before firing, with a plug of mud scooped up from the trench wall.

Setting up 3rd Division Workshop.

The sappers, with the surviving mortar, withdrew under cover of darkness and once in their billets spent the next three days learning everything they could about the mortar before returning it to Bateman, taking with them six lengths of boiler tube, 93 mm internal diameter and 60 cm long, to make up into trench mortars using the facilities of the I Corps workshop. Having no bomb factory of his own, Denning took up residence and, on December 18th, his small command was increased by the addition of two fitters to work on the mortars and two carpenters to make range blocks for firing rifle grenades, with a further addition on Christmas Day of 6 more carpenters and two fitters. Denning’s first mortar was test-fired on December 23rd, and by January 4th, they had manufactured sufficient mortars for the 3rd Division to start training crews to form their first mortar battery.

[1] TNA: WO95/1397: Commander Royal Artillery 3rd Division. War Diary, December 1914, Appendix D,