British units that reached the summit of Chunuk Bair early on 8 August 1915 to engage the Turks were the Wellington Battalion of the New Zealand and Australian Division, 7th (Service) Battalion, Gloucestershire Regiment, and 8th (Service) Battalion, Welch Regiment, both of the 13th (Western) Division. The troops were reinforced in the afternoon by two squads of the Auckland Mounted Rifles Regiment, also part of the New Zealand and Australian Division. The first troops on the summit were severely depleted by Ottoman return fire and were relieved at 10:30 pm on 8 August by the Otago Battalion (NZ), and the Wellington Mounted Rifles Regiment, New Zealand and Australian Division. The New Zealand troops were relieved by 8:00 pm on 9 August by the 6th Battalion, Loyal North Lancashire Regiment, and 5th Battalion, Wiltshire Regiment, who were massacred and driven off the summit in the early morning of 10 August, by an Ottoman counter-attack led by Mustafa Kemal.