She shared many of Bruce's interests, especially golf, and his political outlook. They married in July 1913 in a quiet ceremony. Theirs was a close-knit relationship they would have many acquaintances but a small circle of close friends, and their relationship was one of mutual devotion. But the death of all but one member of his immediate family in just over a decade, and the fact that the Bruces would bear no children of their own, deeply affected Bruce. His brother Ernest's daughter, Helen Bruce, came to play a large part in his life and was to become the main beneficiary of his Will but Bruce "was left with a sense of insecurity and melancholy". Bruce returned briefly to Australia in 1914, swapping positions within the company with his brother Ernest. World War I broke out in August of that year. Bruce and his brothers sought to enlist in defence of the Empire, but all three of them would choose to serve in the British Army rather than the Australian Imperial Force. It was easier to obtain officer commissions in the British Army and the family had a close association with (and for many of them, long periods of residency in) Great Britain. Bruce enlisted and received a commission as lieutenant on 7 February 1915 and was attached to the 2nd Battalion, Royal Fusiliers in Egypt, which was then assigned to the British 29th Division. The 29th subsequently joined operations in Turkey along with Australian and New Zealand Army Corps (ANZAC) troops that year under Sir Ian Hamilton, commander of the Mediterranean Expeditionary Force (MEF). First Lord of the Admiralty Winston Churchill had devised a strategy of capturing the Dardanelles from Turkey to allow naval access to Allied Russia. However allied naval forces were unable to secure passage through the narrow straits, and the MEF under Hamilton devised a plan to wrest control through amphibious landings. This was the beginning of the now infamous Gallipoli Campaign. Bruce's regiment landed at Cape Helles in mid-1915, where he fully distinguished himself in the construction of trenches and as an able commander. His battalion suffered heavy casualties over the coming months, and Bruce himself was wounded on 3 June by a shot to the arm, though it was this injury that spared him from a major assault by his battalion on 4 June in which many of his peers perished. He later reflected that he must have been kept on earth for some purpose. He returned to the front lines and his division moved to the new front at Suvla Bay, where it was involved in particularly heavy fighting and sustained trench warfare throughout August and September.