Vice-Admiral Lachlan Donald Ian Mackinnon, CB, CVO (2 December 1882 – 11 October 1948) was a Royal Navy officer, especially noted for his role as a convoy commodore during the Second World War.

[1] He received the China Medal for service in the Boxer Rebellion,[1] was promoted to acting sub-lieutenant on 15 November 1901, and subsequently confirmed in that rank from the same date.

[1] After that, he was appointed in command of the 2nd Battle Squadron in 1937 with his flag aboard HMS Royal Oak before retiring as a vice admiral on 11 January 1939.

The slow convoy of 35 ships sailed on 5 October 1940 bound for the United Kingdom with a very inadequate escort.

The signals crew was important as the convoys maintained radio silence to avoid detection by the German navy.

That night all three escorts went off in various direction pursuing reports of U-boats or rescuing survivors of the two ships hit early the next morning.

On 19 October, as the convoy approached the British Isles, Mackinnon sighted a U-boat 100 yards ahead.

Assyrian went full ahead to ram her, making 10 knots for the first time in recent memory and chasing the enemy ship for 40 minutes.

The Grimsby-class sloop HMS Leith found him at the very end of his strength, unable to swim or grasp a rope.