by Lieutenant General Sir Archibald Murray with headquarters at Ismailia. After the evacuation from Gallipoli the total British force in Egypt was nearly 400,000 men in 13 infantry and mounted divisions, a force regarded as the strategic reserve for the whole Empire. In March 1916, Sir Archibald Murray took command of all these forces which were united into the new Egyptian Expeditionary Force. Murray believed a British advance into the Sinai to occupy Qatiya/Katia would be more cost effective than the static defences recently established. The War Office agreed to this, but not to his more ambitious plan to advance to the Ottoman border. He believed that the area captured in an advance to El Arish or Rafa could be held with fewer troops than would be needed for a passive defence of the Suez Canal. Murray had estimated a force of 250,000 could cross the Sinai and that 80,000 troops could be maintained in the Katia area. If such a large Ottoman force were to reach Katia then the British would need a very large force to defend the Suez Canal. British occupation of the oasis area which stretched eastwards from Romani and Katia to Bir el Abd along the ancient silk road would deny drinking water to any Ottoman invasion force. Murray planned a 50,000-strong garrison in the Katia area and obtained authority to build a pipeline to pump fresh Nile water and a railway to transport the infantry divisions and their supplies. He also decided to empty the water cisterns at Moya Harab so the central Sinai route could not again be used by Ottoman columns advancing from Palestine and to maintain some troops at Suez to defend the town. These operations began in February 1916 when construction started on the stretch of 4-foot 8 inch standard gauge Sinai railway and water pipeline from Qantara/Kantara to Qatiya/Katia. By the end of March or early in April of track, including sidings, had been laid. Raid on Jifjafa The intact water cistern and wells on the central road across Sinai still enabled Ottoman Army forces to threaten the Canal at any time. Between 11 and 15 April, 25 Bikaner Camel Corps, 10 Engineers with 12 men from 8th Light Horse Regiment and 117 men from 9th Light Horse Regiment (30 light horsemen armed as Lancers), with 127 Egyptian Camel Transport Corps travelled to destroy a well-boring plant, gyns erected