 Complete the following phrase:  121st Siege Battery, RGA, was raised at Pembroke Dock on 22 March 1916 under Army Council Instruction 701 of 31 March 1916 with a cadre of 3 officers and 78 other ranks from the Glamorgan RGA. It went out to the Western Front in July 1916, manning four 9.2-inch howitzers. It joined I ANZAC Corps in Fifth Army on 15 July in time for the 