 By the beginning of December the railway had reached Bir el Mazar and with the development of lines of communications, garrisons, support and services, it became possible to plan for an advance to El Arish.On 21 December, after a night march of the Anzac Mounted Division, commanded by Chauvel, entered El Arish, which had been abandoned by the German and Turkish force who had retreated to Madghaba where the mounted force won a fierce daylong engagement against strong well constructed defences manned by determined defenders.Situated on the British right flank, the Egyptian outpost of Magdhaba was some to the south-south-east into the Sinai desert, from El Arish on the Mediterranean coast.