Before the First World War, he played rugby for Cartha Queens Park RFC and was a member of the 3rd Battalion of the Lanarkshire Rifle Volunteers.

He was a sergeant in the 17th Battalion (Glasgow Commercials), The Highland Light Infantry, British Army during the Battle of the Somme in First World War.

For most conspicuous bravery and devotion to duty, when, having with his party captured a post apparently of great importance to the enemy, he was subjected to severe counter-attacks, which were continuous throughout the whole day.

Although his party was wiped out and replaced several times during the day, Serjeant Turnbull never wavered in his determination to hold the post, the loss of which would have been very serious.

Almost, single-handed, he maintained his position, and displayed the highest degree of valour and skill in the performance of his duties.