Keeping his rank, he was appointed as second-in-command of the 2nd Light Horse Regiment, on 19 August. On 24 September 1914, Glasgow embarked for the Middle East, arriving in Egypt where the light horsemen undertook training until they were transferred Anzac Cove in a dismounted role, to reinforce the infantry that had landed there in April 1915. First World War After the arrival of the light horsemen at Anzac in mid-May 1915, the commander of the 1st Light Horse Brigade, Colonel Harry Chauvel, assumed control of Monash Valley. Following a reorganisation of the defences at Pope's Hill, Glasgow became second-in-command to the commander of the 3rd Light Horse Regiment, Lieutenant Colonel Frank Rowell. While troops from the 1st, 2nd and 3rd Light Horse Regiments rotated through the position on weekly basis, Rowell and his staff remained to oversee the position. However, Rowell became ill and died in early August, after which Glasgow assumed command of the position. On 7 August 1915, Glasgow led an attack on Dead Man's Ridge; the ridge had sweeping views of The Nek. The assault secured part of the Turkish trenchline, but after the failed attack on the Nek, Glasgow, realising that the ridge would now be subjected to a strong counter-attack, ordered a retreat. Bringing up the rear, Glasgow, carried one of the wounded back as the Australians withdrew. Of the 200 men who had taken part in the attack, 60 had been killed, and another 94 wounded, including every officer except Glasgow. In the aftermath, Glasgow was promoted to lieutenant colonel and given command of the 2nd Light Horse Regiment. In December 1915, the Allied forces withdrew from Gallipoli. In the aftermath, the Australian government decided to expand the AIF in Egypt prior to its commitment to the Western Front. As part of this process, the 13th Brigade was raised from a cadre of experienced personnel from the 3rd Brigade and reinforcements from Australia. Glasgow was given command of the new brigade in March 1916. He commanded the brigade for the next two years, including their first major action in September 1916, at Mouquet Farm. Later, the brigade fought around Messines in June 1917, Polygon Wood in September and Dernancourt in early April 1918, where the brigade fought a defensive action that helped halt the German Spring Offensive. After the Germans captured Villers-Bretonneux in mid-April 1918, Glasgow's brigade was assigned to launch a counterattack