After the outbreak of War with Italy HMS MEDWAY and Submarines of the 4th Submarine Flotilla were sent from Hong Kong to the Mediterranean to be based at Alexandria in Egypt. HMS RAINBOW (Lt Cdr L P Moore) sailed on 23 September 1940 from Alexandria to a patrol area off Calabria.

Even to this day, there remains some confusion as to her fate. According to A S Evans in ‘Beneath the Waves’ (the reference quoted most often), HMS TRIAD – on patrol in an adjacent area – was probably lost through mining, and that source also states that HMS RAINBOW was sunk in an action with the Italian submarine, ENRICO TOTI. However, various sources now claim (since 1988) that the submarine sunk by ENRICO TOTI was in fact TRIAD and that HMS RAINBOW was not even in the same area at that time.

Neither submarine wreck has been surveyed, which leaves analysts with area allocations, orders and reports as the only evidence available to provide proof of identity from situations which were often fluid and confusing at the time.

It is now believed that, on 4 October 1940 while attacking a convoy, RAINBOW collided with the Italian MV Antonietta Costa. HMS RAINBOW was lost with All Hands.