 The plan called for the 1st and 2nd Light Horse Brigades , the 5th Mounted and the New Zealand Mounted Rifles Brigades to swing round the attackers ' left flank and <unk> them . The first reinforcements to arrive were the Composite Regiment of the 5th Mounted Brigade ; they came up on the flank of their mounted regiment ; the Royal Gloucestershire Hussars ' " D " Squadron 1 @,@ 500 yards ( 1 @,@ 400 m ) west of Mount Royston , which was being attacked by a strong body of Ottoman soldiers . The regiment attacked the Ottomans in enfilade and forced them back . 
