 The group dived with Davis Escape Sets, which until then had not been used much if at all for swimming down from the surface.At first they swam by breaststroke without swimfins.On 17 December 1942, during one such attack, two of the Italian frogmen (Lt. Visintini and Petty Officer Magro) died, probably killed by small explosive charges thrown from harbor-defence patrol boats, a tactic said to have been introduced by Crabb.