In 1917 Acting First Lieutenant Donald Fairfax Mackeson lost his life on 1 December whilst securing a buoy in heavy weather and after dark on HMS Tower. He was later commended by his senior officers "as being an example of fearlessness in the face of danger, and also of great devotion to duty, of which will not be forgotten as long as the flotilla exists."

He is a notable loss as he was the grandson of Rear Admiral John Moresby and great-grandson of former Admiral of the Fleet Sir Fairfax Moresby, and most notably, the only descendant of either Admiral Moresby to be in the Royal Navy during World War I. He is commemorated on the Chatham Naval Memorial as well as the East Lavant War Memorial. http://en.wikipedia.org/wiki/HMS_Tower_(1917)