HMS Union was a British U class submarine, of the second group of that class, built by Vickers Armstrong, Barrow-in-Furness.

Union spent much of her short career operating in the Mediterranean, where she sank the Italian merchant Pietro Querini.

Union sailed from Malta at 1 o’clock on the morning of 14 July 1941 with orders to intercept a convoy north of Tripoli the following day.

On 20 July 1941 she was depth charged by the Italian torpedo boat Circe, and sank with all hands during the attack on the convoy south of Pantelleria.

When Union failed to return to Malta she was reported overdue on 22 July 1941.