Jacka enlisted in the Australian Imperial Force on 18 September 1914, with the rank of private. He was assigned to the 14th Battalion,4th Brigade, 1st Division and finished his training at Broadmeadows Camp.After Turkey became a German ally, the 1st Division was sent to Egypt to defend the Suez Canal. Jacka and his battalion arrived at Alexandria on 31 January 1915. During ten weeks of training south of Cairo the 4th Brigade was merged with two New Zealand brigades and merged with the 1st Light Horse Brigade to form the New Zealand and Australian Division (NZ&A) under Major General Alexander Godley.
