91st Siege Battery (91st SB) was a heavy howitzer unit of Britain's Royal Garrison Artillery (RGA) in World War I. Formed in December 1915, it served on the Somme and the Ancre, at Arras and at Messines. It was then stationed on the Flanders coast where it took part in months-long artillery duels. In 1918 it fought against the German Spring Offensive and participated in the final Allied Hundred Days Offensive. The battery was disbanded after the war.
Mobilisation and training Once the fighting on the Western Front had bogged down into Trench warfare in 1914, there was an urgent need for siege artillery, and a large number of new RGA units were hurriedly formed over the following years.Farndale, Annex E. On 24 November 1915 the War Office instructed that 91st Siege Battery would be formed as a heavy howitzer battery at Plymouth on 1 December.War Office Instruction No 276, 24 November 1915.Frederick, pp. 702–7. Temporary Major William Christian, who had served on the Western Front with 34th Siege Battery, arrived to take command. The battery had a nucleus of Regular Army non-commissioned officers (NCOs) from the Siege Depot at Cooden Camp, Bexhill-on-Sea, and the other ranks (ORs) were selected from the RGA at Plymouth. Although the first rush of volunteering was long over, Christian noted that the battery's ORs were all 'Kitchener's Army' volunteers and were keen to serve alongside their friends and relatives.Christian, pp. 1–3.RGA Depots and Training Brigades at Long, Long Trail.
After about a month's training at Plymouth the battery moved to Horsham where it had the use of guns, directors, dial sights and signalling equipment at the School of Artillery established there. In mid-April the battery moved to the camp at Lydd where training continued and it fired six practice shoots with 6-inch and obsolete 8-inch howitzers. The battery was informed that it was to be equipped with 9.2-inch howitzers and on 5 May it was sent to Bristol to mobilise for overseas service. The four guns and associated stores began arriving on 7 May, and on 23 May the battery transport arrived. Manned by two officers and 95 ORs of the Army Service Corps (ASC), it comprised 33 lorries, one car (a Daimler 18-20 known within the battery as 'Mimi'), five motorcycles and the four Holt caterpillar gun tractors. An RGA advance party went by way of Southampton Docks to Le Havre in France, and a joint RGA/ASC party went to Avonmouth Docks to oversee the embarkation of the guns and transport. The remainder of the personnel left Bristol on 25 May and went by train via London to Folkestone Harbour where they embarked at 17.30 and arrived at Boulogne that night to join the British Expeditionary Force (BEF).91st Siege Battery War Diary, 1 May 1916–February 1918, TNA file WO 95/477/7.Allocation of Siege Batteries RGA, TNA file WO 95/5494/4.Allocations of 81st–100th Siege Btys at Long, Long Trail.
Western Front Once the various parties of 91st SB had concentrated at Boulogne, the gunners left by lorry on 1 June for the Doullens area, while the guns and tractors went by rail. The battery reached its assigned positions at Pommier on 2 June, when it joined 19th Heavy Artillery Group (HAG) in Third Army. The gunners began laying gun platforms and constructing dugouts, and in so doing discovered an old shaft with chambers left by former chalk mining. After miners among the battery's personnel had dug an intercepting tunnel these chambers were capable of accommodating the whole battery below ground. By 10 June the battery had brought the first three howitzers up after dark and had camouflaged them in an orchard on the south side of Pommier.Christian, pp. 3–4.Macdonald, Pro Patria Mori, pp. 188–9, Map 8.19th HAG War Diary June 1916–March 1917, TNA file WO 95/217/2.
Gommecourt 19th HAG was assigned to support VII Corps' Attack on the Gommecourt Salient in the forthcoming 'Big Push' (the Battle of the Somme). Its main role was to use the high-angle fire of its howitzers to bombard German trenches and strongpoints facing 56th (1st London) Division's attack frontage on the south face of the salient. 91st SB's position north-west of the salient had been chosen to bear on these trenches from the rear and also on nearby battery positions. On 12 June the battery registered all four guns on a point in the German trenches directed by the observation post (OP) codenamed 'Wagram'. One shell fell exactly on an important trench junction, and next day the gunners could see that the enemy had erected an ironic bull's-eye target on this spot. The following days were spent improving the battery positions and dumping ammunition at the guns, registering targets and carrying out counter-battery (CB) fire against hostile batteries with aircraft observation.Christian, pp. 4–5.
VII Corps' bombardment plan for the operation was issued on 16 June. It was spread over five days, designated U, V, W, X and Y, before the attack on Z Day. The heavy howitzers joined in the bombardment on 25 June (V Day). The planned rate of fire was 50 rounds per gun on V to X days, then 70 rounds on Y day. Ammunition for the modern howitzers like the 9.2-inch was in short supply, and had to be carefully rationed during the preliminary bombardment. At all times during daylight, No 8 Squadron, Royal Flying Corps (RFC) had a BE2c observation aircraft in the air spotting fall of shot for 19th HAG's batteries. Among the targets for 91st SB were 'Nameless Farm' and 'Farmyard Strongpoint', the strongpoints at Gommecourt Cemetery and 'The Maze', the 'Exe' 'Ems' and 'Epte' communication trenches, and the line of trenches ('Mess', 'Mere', "Meed' and 'Meet') running along the top of the ridge into Rossignol Wood. Although 19th HAG was the designated bombardment group and 48th HAG was the CB group, 91st SB carried out a number of CB shoots directed by No 8 Sqn, its 9.2-inch shells supplementing the lighter 60-pounders of 48th HAG. On V Day it fired 15 shells at a battery spotted just south of Biez Wood, the second of which caused a large explosion. It was then called up by an RFC Kite balloon to fire on one of the battery positions around Le Quesnoy Farm. It fired 25 rounds but their fall was unobserved. On W Day (26 June) 91st SB recorded three excellent CB shoots, optimistically claiming three batteries destroyed. Poor weather hindered observation on X Day, but 91st SB joined in with 48th HAG in a six-minute 'sweep' of the area south from Adinfer Wood to Le Quesnoy Farm. On 28 June No 2 gun suffered a premature explosion of a faulty shell in the bore of the gun. This caused a large bulge in the barrel and forced out the sides of the cradle. Both gun and carriage had to be condemned, but luckily no-one was injured. The battery took over a replacement gun from 90th SB. VII Corps ordered an all-out bombardment of enemy battery positions on Y Day, but because of bad weather this had to be done 'off the map' without direct observation. 91st SB fired 40 rounds on the batteries south of Le Quesnoy Farm, but this effort was soon called off. Because of the poor weather the attack was postponed for two days, and the additional days (Y1 and Y2) were used for further bombardment, though limited by shell supply. On Y1 91st SB put down a fast and accurate 'strafe' on 'Stellung 508' east of Essarts: nine out of 16 shells were observed by the RFC to hit the target. It contributed another 30 rounds of CB fire on Y2.Edmonds, 1916, Vol I, pp. 299–307.MacDonald, Pro Patria Mori, pp. 179–82, 201.MacDonald, Lack of Offensive Spirit, pp. 221–2, 237–8, 248–50, 256, 263, 274.48th HAG War Diary August 1915–June 1917, TNA file WO 95/225/1.
A final bombardment began at 06.25 on Z Day (1 July), with 65 minutes of intense fire (2 rounds per gun per minute) before H Hour at 07.30, with 91st SB firing at the trenches south of Gommecourt. The German guns were also hammering 56th (1st L) Division's assembly trenches from 04.00 onwards, causing numerous casualties among the troops waiting to go 'over the top'. At H Hour the German artillery laid a barrage across No man's land, but the leading waves of 56th (1st L) Division had anticipated this and moved out early. They made it to the German front trenches, which they found smashed up by the heavy howitzers, though there were numerous 'dud' 9.2-inch shells lying unexploded and the deep dugouts were undamaged. They quickly secured the first two trenches, but the third, although heavily damaged was strongly manned by German riflemen and machine gunners who had been sheltering in the dugouts. The following infantry waves suffered heavy casualties from the German barrage, fired by batteries that had not been suppressed by the CB bombardments. When the assault was launched two guns of 91st SB were assigned to help 48th HAG with CB fire, but observation was poor due to smoke, and the battery expended its allocation of CB rounds by 12.45 with little result. Apart from the guns bombarding Gommecourt village and park, the rest of the guns of the HAGs lifted off the front trenches at H Hour and begun firing on the flanks of the first objective. After 15 minutes they switched to the second objective, after which they were to shift forward to cover the consolidation of that line. However, the difficulties faced by the follow-up waves of infantry meant that they could not keep up with this timetable, and reinforcements and parties carrying ammunition could not get across No man's land. 46th (North Midland) Division, attacking the north side of the salient had fared much worse, and during the afternoon 56th (1st L) Division's lodgement became untenable. By 21.30 the last surviving parties had withdrawn to their own lines. During the day 91st SB had fired 820 rounds, each shell weighing .Edmonds, 1916, Vol I, pp. 460–4, 471–3, Sketch 24.MacDonald, Pro Patria Mori, pp. 253, 259, 264–5, 409.MacDonald, Lack of Offensive Spirit, pp. 425–9.