He enlisted in the newly formed Welsh Horse Yeomanry in 1915 and the regiment was sent to Gallipoli (it had been converted to an infantry regiment) and carried out mining and sapping duties in the area around Hill 60. They were evacuated to Egypt as part of the last British troops to leave the peninsula. The Welsh Horse provided part of the garrison in the Libyan desert until January 1917, when they were merged with the 1/1 Montgomeryshire Yeomanry and then formed the 25th Battalion, The Royal Welch Fusiliers, British Army. During the last week of October, the 25 RWF were positioned on the right of the 74 Division, in the centre of the line where, along with 24 RWF they were to be the brigade's two attacking battalions. At this time, Collins was 37 years old, and an acting corporal when the following deed took place for which he was awarded the Victoria Cross.