70th Siege Battery was formed at Dover under War Office Instruction No 144 of 9 October 1915 from one company (probably 1/4th Company) of the Forth RGA, which provided half the personnel. It went out to the Western Front on 26 March 1916 armed with four 8-inch howitzers and joined the Northern Heavy Group (40th Heavy Artillery Group or HAG) in X Corps. This Corps was part of Fourth Army preparing for that summer's 'Big Push' (the Battle of the Somme).