Commonwealth Military Forces, and Weir was appointed adjutant. He was promoted to major on 1 January 1904, and appointed as regimental second-in-command. He was awarded the Long Service and Good Conduct Medal in 1905, and the Volunteer Officers' Decoration in 1908. On 22 June 1908, Weir was promoted to lieutenant colonel and appointed the commanding officer of the 10th Infantry Regiment. On 1 January 1912, he was transferred to the unattached list but this only lasted until 1 July, when the universal training scheme was introduced. He was soon appointed to command the 19th Infantry Brigade, and on 9 September 1913 he was promoted to colonel. World War I On 12 August 1914, Weir received a telegram from Colonel Ewen Sinclair-Maclagan, the designated commander of the 3rd Brigade, offering him the command of the 10th Battalion. Weir promptly accepted, and on 17 August was appointed as a lieutenant colonel in the Australian Imperial Force (AIF), making him the first South Australian to be commissioned in the AIF. He retained his rank of colonel in the part-time forces in an honorary capacity. Gallipoli Weir assembled and trained his battalion at the Morphettville Racecourse, then embarked with them on the transport Ascanius on 20 October 1914 as the first convoy of Australian troops departed for overseas service. On arrival in Fremantle, six companies of the 11th Battalion were embarked on the transport, and Weir was appointed Officer Commanding Troops for the voyage. The troops began disembarking at Alexandria on 6 December 1914, and were entrained for Cairo, where they began to set up camp at Mena. The Australian Official War Historian, Charles Bean, described Weir as being "somewhat above average in years" for a battalion commander. Following the Allied decision to land a force on the Gallipoli Peninsula, the 3rd Brigade was selected as the covering force for the landing at Anzac Cove. The 10th Battalion embarked for the Greek island of Lemnos in the northern Aegean Sea on 1 March 1915, and after further training on Lemnos, the battalion was one of the first two battalions ashore on the morning of 25 April 1915. During the landing, when the boats carrying the lead elements of the battalion were around from shore, according to Bean, Weir observed to another officer in his boat that everything was silent, but soon after Ottoman troops began firing at the landing force. Weir landed with the