William McLauchlan enlisted on 19 August, 1914. He was 26 years old, single and working as a tailor at 130 McKillop St., Geelong. He had been  born in Aberfeldy, Perthshire, Scotland and cited 7 years military experience with the Black Watch (3rd Battalion, Royal Regiment of Scotland) prior to coming to Australia. He was 5' 9" tall and by faith, Presbyterian. 

William McLauchlan enlisted on 19 August, 1914, and was placed with the 6th Training Battalion, and immediately made Corporal. He was then placed in the 5th Battalion, one of the first battalions for the A.I.F. and raised in VictoriaOn 21 October, he embarked for overseas service on board the A3 Orvieto, sailing first to Albany, Western Australia to join the rest of the expeditionary force, then to Egypt, arriving on 1 December. On 5 April 1915,  the 5th Battalion proceeded to join the M.E.F. (Mediterranenean Expeditionary Force), the part of the British Army that commanded all Allied forces at Gallipoli and Salonika. This included the initial naval operation designed to force open the Straits of the Dardanelles. It was at first commanded by General William Birdwood, commander of the Australian and New Zealand forces, but for the duration of the Gallipoli campaign, General Charles Munro led the M.E.F.

The 5th Battalion formed part of the second assault wave on 25 April, and on storming the beach, William McLauchlan was wounded in the abdomen. In 1967, his son wrote to the department,  asking that his father be awarded a Gallipoli Medallion:

... my father, William John McLauchlan was an Origonal Anzac, his regimental number 113. His unit on Gallipoli was the 5th Battalion. To our knowledge, he was wounded on the first day of the landing and lay on the beach for 3 days before being rescued.

This doen't accord with his army record, which has him with shrapnel wounds in his back, and admitted to Alexandria Government Hospital on 26 April, 1915. He was sent to England for further treatment on 2 July on the Hospital Ship Delia  and on 27 July, was admitted to the 2nd West General Hospital in Manchester, with again with shrapnel wounds to his back. It must have been a very painful and difficult time for him.

On 27 July, 1915 he was transferred to Woodstock Park, Epson and on 28 July, to the City of London War Hospital, aslso in Epsom. It wasn't until 15 March, 1916, that he was finally able to rejoin the army and on 4 May, was taken on strength at Montevideo, Chickerell, Weymouth. This was a military camp, the first one with huts, and a cookhouse, shower block, gymnasium and orthopaedic recovery unit. Preumably, he was there to recuperate from his wounds.

William McLauchlan stayed at Montevideo until early 1017. It must have been a hard time for him and perhaps he felt constrained by the camp. On 22 June, he was placed in Great Peters Square Hospital and had his pay stopped for 20 days as a result from 30 March to 18 April, 1916. On 1 January, 1917, he was again out of camp, going A.W.L.  for 24 hours and forfeiting another two days pay.

His time in Montevideo being up, he was placed in a training role on his release. ON 27 January,i he marched in to the Infantry Draft Depot and was appointed to A.F. Corps at N0.6 Perham Downs camp.After three months, on 22 June, 1917, he was attached to the 30th Training Battalion and promoted to Warrant Officer. he was taken on strength on 11 August. He stayed with the 30th Training Battalion until 17 May, 1918, when he was promoted to Sergeant-Major Class 1.

With the war over in November 1918, William John McLauchlan left Britain for Australia on 3rd December, 1918,  on board the Port Hacking and disembarking in Melbourne on 27 January, 1919. He was discharged from the army on 28 March, 1919. He had served for the full length of the war, from 1914-1919. 

William McLauchlan went back to Geelong and resumed his occupation as a tailor at 130 McKillop st., Geelong. The same year that he returned, he married Margaret Mary Seargeant, also from Geelong and a saleswoman. They had one child, a son,  John Relvie McLauchlan, a labourer. William died in 1956 and was buried at Geelong Eastern Cemetery. He was survived by his wife, Margaret Mary, and his son John Relvie McLauchlan. John died in 1967 and Margaret in 1975.