Somme

On 2 June the battery brought up its No 1 gun and got it into position during the night under its 'haystack'. On 14 June No 2 gun was got into position near Vivier Farm. On 16 June No 1 gun fired four rounds for registration against Mametz Church. On 24 June both guns fired for registration, No 2 at Fricourt Farm. Then on 26 June the battery joined in the preliminary bombardment for the attack on 1 July. The two howitzers each fired 45–68 rounds per day at Fricourt and Fricourt Farm; at one point No 1 gun crew achieved seven rounds (each weighing 750 pounds (340 kg)) in 11 1⁄2 minutes. The recoil was so great that the railway embankment from which No 1 gun was firing began to settle, and it had to cease fire until the Royal Engineers (RE) could shore it up. Despite the weight of shelling the first day's assault on Fricourt was a failure, and its capture had to be completed on 2 July.^{[7][8][9][10]}

While No 1 gun fired at Contalmaison, No 2 gun moved near to Bray-sur-Somme on 5 July, then No 1 moved alongside on 8 July. The bombardment of the German second line began on 11 July: No 1 blew up an ammunition store while No 2 was reported to have set fire to Martinpuich Church and to have destroyed an anti-aircraft gun. The attack on the second line (the Battle of Bazentin Ridge) went in on 14 July and the guns fired on Martinpuich and Bazentin-le-Petit.^[7][8][11]

Over the next three months of the Somme offensive 44th SB continued to engage targets such as High Wood, Delville Wood, Switch Trench, Guillemont, and Ginchy, each the scene of bitter fighting. Firing was often in cooperation with observation balloons and occasionally with aircraft. On 31 August the No 1 gun (No 10 in order of manufacture) was showing signs of wear and was allocated its last 50 rounds. It was replaced by gun No 34 on 6 September, but this lasted only 152 rounds before it suffered torn rifling and was also condemned on 15 September during the Battle of Flers–Courcelette. While No 2 gun continued firing at Gueudecourt, No 1 was sent to Le Havre for replacing. No 2 gun was condemned on 27 September for scoring of the barrel after 1956 rounds fired, but gun and mounting No 40 arrived on 30 September as the battery's new No 1 gun.^[7][8][12]

XV Corps' participation in the Somme Offensive ended with the Battle of Le Transloy (1–18 October), after which 44th SB was transferred to 69th Heavy Artillery Group (HAG) on 23 October. It continued firing at various targets until the end of the year.^[5][6][7][8]

Vimy

The practice at this stage of the war was to switch batteries and HAG headquarters around as required. 44th Siege Battery moved to 23rd HAG on 27 January 1917, then on 3 February it got orders for an immediate move, joining I ANZAC Corps with Fifth Army on 6 February for the Operations on the Ancre, January–March 1917.^{[5][6][7][13]} Next it was with First Army, first with 55th HAG, then from 18 March with 26th HAG.^{[5][6][7][14]}

First Army was preparing for its part in the forthcoming Arras Offensive, the attack on Vimy Ridge planned for 9 April. The role of heavy howitzers was clarified in early 1917, when it was recognised that they were best suited for counter-battery (CB) fire against well-protected enemy guns. For Vimy there were dedicated CB groups with observation aircraft, beginning 20 days before the attack (Z minus 20) with systematic fire, then from Z minus 10 switching to more vigorous destruction of all known enemy batteries, telephone exchanges and observation posts. First Army's commander, Gen Henry Horne was himself a gunner and took personal command through his Major-General, Royal Artillery, Maj-Gen H.F. Mercer, of the heaviest 15-inch and 12-inch guns. 26th HAG was firing in direct support of the Canadian Corps attacking on Vimy Ridge itself. The huge weight of artillery, including 'some of the most accurate counter-battery fire of the war', together with the dash of the Canadians ensured the success of the attack.^[14][15]

Successes dwindled as the Arras offensive continued, though the guns continued their support. In May 44th SB brought CB fire and direct bombardment onto Mericourt. But CB fire could work both ways: on 28/29 May the battery suffered two men wounded and cartridge dugouts destroyed by enemy guns.^[7][14]

Cambrai

44th Siege Battery continued its CB duties from June to October 1917, then between 12 and 18 November it was transported to join 90th HAG with Third Army, preparing for the Battle of Cambrai. The massed guns were kept silent until the surprise attack was launched in 20 November, but their positions and targets were accurately surveyed so that they could fire 'off the map' without need for prior registration. The 'super heavy' artillery group fired concentrations on the villages behind the lines, 44th SB firing on Havrincourt, Flesquières and Graincourt, major objectives for the attack. The attack was a great success, but its exploitation was disappointing. 44th Siege Bty switched to the command of 58th HAG on 25 November during the fighting for Bourlon Wood and then the German counter-attacks that wiped out the gains of Cambrai.^{[5][6][7][16][17]}

Battles of 1918

44th Siege Battery remained with Third Army during the winter of 1917–18, under 87th HAG from 15 December to 26 February 1918.^[5][6] In early 1918 the BEF changed its heavy artillery organisation. The HAGs became permanent RGA brigades, but the heaviest guns (including 44th SB's railway howitzers) remained unbrigaded under the direct command of Army HQs. The battery operated under Third, First, Fifth and Fourth Armies during the German spring offensive and Allied Hundred Days Offensive of 1918. As the fighting became more fluid the heaviest artillery became less useful, the railway guns in particular being dependent on the rate at which the RE could repair the destroyed lines in the battle zone. When hostilities ended in November, 44th SB was operating under Fifth Army.^[18][19]