still using the same system that he had cracked during the Spanish Civil War; he instructed his assistants to use rodding to see whether the crib PERX (per being Italian for "for" and X being used to indicate a space between words) worked for the first part of the message. After three months there was no success, but Mavis Lever, a 19-year-old student, found that rodding produced PERS for the first four letters of one message. She then (against orders) tried beyond this and obtained PERSONALE (Italian for "personal"). This confirmed that the Italians were indeed using the same machines and procedures. The subsequent breaking of Italian naval Enigma ciphers led to substantial Allied successes. The cipher-breaking was disguised by sending a reconnaissance aircraft to the known location of a warship before attacking it, so that the Italians assumed that this was how they had been discovered. The Royal Navy's victory at the Battle of Cape Matapan in March 1941 was considerably helped by Ultra intelligence obtained from Italian naval Enigma signals. American bombes Unlike the situation at Bletchley Park, the United States armed services did not share a combined cryptanalytical service. Before the US joined the war, there was collaboration with Britain, albeit with a considerable amount of caution on Britain's side because of the extreme importance of Germany and her allies not learning that its codes were being broken. Despite some worthwhile collaboration amongst the cryptanalysts, their superiors took some time to achieve a trusting relationship in which both British and American bombes were used to mutual benefit. In February 1941, Captain Abraham Sinkov and Lieutenant Leo Rosen of the US Army, and Lieutenants Robert Weeks and Prescott Currier of the US Navy, arrived at Bletchley Park, bringing, amongst other things, a replica of the 'Purple' cipher machine for Bletchley Park's Japanese section in Hut 7. The four returned to America after ten weeks, with a naval radio direction finding unit and many documents, including a "paper Enigma". The main American response to the 4-rotor Enigma was the US Navy bombe, which was manufactured in much less constrained facilities than were available in wartime Britain. Colonel John Tiltman, who later became Deputy Director at Bletchley Park, visited the US Navy cryptanalysis office (OP-20-G) in April 1942 and recognised America's vital interest in deciphering U-boat traffic. The urgent need, doubts about the British engineering workload and slow progress prompted