Nothing is known about Thomas McGarry's life, except that regimental records published after the War show he had been born in the Stockport area and enlisted into the army in the town. His service number suggests he probably enlisted in the late autumn of 1914 or early in 1915, going overseas a few months later.
On 20 May, Thomas and and his comrades took over a section of the front line near the village of Monchy-le-Preaux (5 kilometres to the east of Arras). The following days were relatively quiet and the men followed the usual trench routines of sentry duty, sleeping and trying to dodge the enemy shelling. On the 27th, orders were received for a night attack to be undertaken on German positions at Infantry Hill, east of the village. The assault would be in conjunction with the 16th Middlesex on their right and 8th East Lancashires on the left.
The Regimental History describes what happened. "At 10.30pm, "D" Company (2nd Lt R H Stubbs) which was to carry out the assault began crawling forward to a tape laid parallel to the objective. They were followed by the supports "A" and "C". By 11.15 they were all in position. But, owing to the moonlight and his own flares, the enemy evidently detected this movement for he put down a heavy barrage with artillery and machine guns on the front and support lines. At zero, 11.30pm, an intense barrage opened on the German trenches and the Battalion began its advance. The enemy appeared to be leaving his positions and a premature message was received stating the objective had been taken. But in fact the attack was held up on the right and only the left flank succeeded in reaching the German trench. Three times, Stubbs led his men forward with the utmost disregard for danger, rallying and reforming them under heavy machine gun fire after each unsuccessful attempt. He was twice wounded, the second time severely. In the end, the attack had to be abandoned and the original line reoccupied. Nevertheless, the Battalion tried, though in vain, to help, with the fire of Stokes mortars, Lewis and machine guns, a party of the 16th Middlesex who were isolated between the two lines. The Battalion's casualties were 1 officer missing and 5 wounded, 6 other ranks killed, 43 wounded and 22 missing".
Thomas was one of those posted as missing. He had, almost certainly, been killed crossing No Man's Land. His body was never recovered and identified.