Four of Henry & Mary Ann Grundle's sons served in WWI:
James Grundle (1892-1916)
Belfast Newsletter, 11 July 1916: ... Jas. Grundle, Derry Vols., Killowen Street, Coleraine, killed.
https://www.cwgc.org/find-war-dead/casualty/787952/grundle,-james/William Henry Grundle (1894-1950) m.(1926) Annie McQuillan & had family.
Belfast Newsletter, 27 May 1916: Lance-Corporal Wm. H. Grundle, Killowen, Coleraine, Royal Inniskilling Fusiliers, has been wounded in the ankle. He is one of four brothers with the colours.
John Grundle (1899)
Northern Whig, 19 Oct.1918: GRUNDLE. Rifleman John Grundle, R.1.R., wounded, is a brother of Mrs. James Holmes, Killowen Street, Coleraine.
Larne Times, 26 Oct.1918: Rifleman John Grundle, Royal Irish Rifles, brother of Mrs. James Holmes, Killowen Street, Coleraine, has been admitted to hospital with a bullet wound in the arm.
Not sure yet which was the 4th son.