 Complete the following phrase:  All four batteries had originally gone out to Egypt with the 2nd Mounted Division in April 1915, but did not proceed to Gallipoli when the division was dismounted for service there. Instead, they variously served on the Suez Canal Defences, as part of the Western Frontier Force in the Senussi Campaign, or in Aden where B Battery, HAC and Berkshire, RHA fought a sharp action at Sheikh Othman that removed the 