Page enlisted in the Australian Imperial Force (AIF) in February 1915, with the rank of private. He was commissioned as a second lieutenant in the 25th Battalion two months later. He arrived at Gallipoli in September, by which time he had been promoted lieutenant. During a nighttime reconnaissance mission on 29 October, Page and another soldier disabled two Ottoman soldiers and threw bombs into enemy trenches. He was wounded in action by enemy shelling in December, but was able to rejoin his unit in Egypt the following month.