AngusMackay is shown as living at home in the 1911 Census with his parents. However he left Tongue to live in Edinburgh with his brother John at 61 Restalrig Road; John was employed as a Detective with Leith Police and was married to Mary Waters from Rhifall in Farr. In Edinburgh, Angus gained employment at Leith Docks; he also joined the Territorial Army serving in the 5 Battalion (Queens Edinburgh Rifles) Royal Scots.

In early 1916 he transferred into the 88 Brigade Machine Gun Corps. He served in Gallipoli in Turkey, Egypt and then on The Western Front in France. He fought at The Battle of the Somme and in the Ypres Salient in Belgium. In April 1917 he took part in the Battle of Arras, where he was wounded and taken prisoner near the village of Monchy- le Preux in France. He then died from his wounds, in a German military hospital at Darmstadt Germany as a prisoner of war on the 5 of May 1917, aged 22years. His parents had been told he was missing in April and Angus had written them a letter from hospital to say he was wounded. The Germans buried him with full military honours in the nearby military cemetery.

Angus was the third son of Mr Alex Mackay to be killed in the First World War; his brothers who both died on Tongue War Memorial ( Trooper D Mackay, A.N.Z.A.C. and Private Magnus Mackay Argylls.) Angus had six other brothers, George who served in the Royal Artillery and won the Distinguished Service Medal, Hugh served in the Army Service Corps in India, they both survived the war and returned home. John and William were both policemen in Leith Police, Sandy worked on a sheep station in the Australian outback and Robbie was a dock-worker.

Mr Alex Mackay receive a letter from the King dated 20-07-15 to thank him, for his patriotic spirit in allowing his sons to serve the colours