Cumberbatch was educated at the Royal Naval Colleges at Osborne and Dartmouth from May 1914, until appointed a midshipman on 15 August 1917. He then served aboard the battlecruiser until January 1919, seeing action at the Second Battle of Heligoland Bight. After serving on several battleships and destroyers, and being promoted to sub-lieutenant in January 1921 and to lieutenant in December 1922, he attended officer training courses before serving as First Lieutenant of the submarines and between 1924 and 1928.