Career
Duff joined the Royal Navy in 1875. He was Director of the Mobilisation Division at the Admiralty from 1912 through the start of the war. He served in World War I as Rear-Admiral (Second-in-Command) of the 4th Battle Squadron, taking part in the Battle of Jutland in 1916.
He then became Director of the Anti-Submarine Division in 1917.
Like the First Sea Lord, Admiral Jellicoe, Duff initially opposed the use of convoys. However, his efforts greatly reduced the destruction caused by the "underwater menace".
After the War he became Assistant Chief of the Naval Staff and then, from 1919, Commander-in-Chief, China Station. He retired in 1925.
