 In early 1917 , the Imperial Mounted Division was formed from the 3rd and 4th Light Horse Brigades and two British mounted brigades . The division first saw service during the First Battle of Gaza , which occurred in southern Gaza on 26 March 1917 . At around noon two mounted brigades of the Anzac Mounted Division attacked Gaza from the north and east . At 6 @.@ 00 pm the Turkish position had become perilous with the ring closing tightly around Gaza . However , in a decision that dismayed most of their soldiers the British commanders decided to call off the attack and retreat , delivering victory to the Turks . A second attempt was made to capture Gaza on 19 April by which time the Turkish defences were even more formidable and the task confronting the British even more difficult . This battle became known as the Second Battle of Gaza . The Anzac Mounted Division played only a minor role in this battle suffering only 105 casualties out of the 5 @,@ 917 suffered . The second battle of Gaza was a disastrous defeat for the Allied forces . 
