On 22 June 1941, HMS UNION (Lt R M Galloway) sank the Pietro Querini (1,000 tons) in a small enemy convoy.

UNION then sailed from Malta on 14 July 1941 to intercept a convoy on 15 July. In the event, she did not attack this convoy but intercepted a second one on 20 July.

UNION fired a torpedo, the wake of which was observed by an escort, the Italian Circe. Circe closed to the point from which the torpedo had been fired and attacked. The captain of Circe saw a periscope beneath the water.

Six further depth charges were launched following which a large bubble of air was observed and, subsequently, a large patch of oil. These are believed to have come from UNION, which was lost with all hands on only her second patrol in the Mediterranean.