late October 1902, when the battalion was stationed at Portsmouth. In 1906 he was appointed adjutant of the Customs and Docks Rifle Volunteers (the 15th Middlesex Rifle Volunteers). When the reserve forces were reorganised into the Territorial Force in 1908, he became adjutant of the successor battalion, the 17th London Regiment (Poplar and Stepney Rifles), remaining with the battalion until 1911. During this time, he married Constance Elizabeth Hamilton; their first child died at birth in 1910. In 1909, he also became the Army and Navy middleweight officers' boxing champion. After a short spell with his regiment in 1911–12, he was appointed to the School of Musketry as an instructor, specialising in machine-guns, and was working here at the outbreak of war in 1914. First World War On the outbreak of the First World War in August 1914, the British Army expanded rapidly, taking in hundreds of thousands of new recruits. Lindsay remained at the School of Musketry until 1915, when he was sent to France as an instructor in the headquarters machine-gun training school, before returning to England later in the year as a staff officer at the newly established Machine Gun Corps training centre. Lindsay had been a strong advocate of the centralisation of machine-gun units, concentrating them in specialised companies and battalions rather than distributed to individual infantry units, and the Corps had been formed to man them. The training for these units could focus on offensive as well as defensive operations, using heavy machine-guns in an indirect fire role, which provided substantially greater capability and flexibility in combat. In 1916, Lindsay was given a front-line posting, as the brigade major of the 99th Brigade (United Kingdom), a New Army formation primarily composed of London volunteers from the Royal Fusiliers. He served with the 99th through the Battle of the Somme and Battle of Arras, receiving the Distinguished Service Order. In March 1918 he was promoted to colonel and made a staff officer at the First Army headquarters, responsible for the Army's machine-gun units. Following the Armistice, he commanded the 41st Battalion, Machine Gun Corps, in the Army of Occupation in Germany. Inter-war years Following the reduction in forces after the end of the war, the Machine Gun Corps units were disbanded and Lindsay attended the Staff College, Camberley in 1920. After leaving Camberley, he was appointed to command an armoured car unit in Iraq. The British