On 20 December, a week after Chauvel returned from leave, the advance to El Arish began when the Anzac Mounted Division left Bir Gympie at 21:45. They moved out without the 2nd Light Horse Brigade, which was in the rear assisting with patrolling the lines of communication stretching back to Kantara on the Suez Canal. So it was the 1st and 3rd Light Horse Brigades, the New Zealand Mounted Rifles Brigade, the 5th Mounted Brigade and the newly formed battalions of the Imperial Camel Brigade with the mountain guns of the Hong Kong and Singapore Camel Battery which made the trek to El Arish.