If I'm not mistaken the Japanese had two types of B5N carrier-based bombers: the B5N1 and the B5N2
(B5N1) Three-seat carrier-based bomber
* Navy Type 97 Carrier Attack Bomber Model 11 (B5N1 Model 11).
* One 7.7 mm machine-gun, manually-aimed, in rear cockpit
Underwing racks for two 250 kg bombs or six 60 kg bombs
* Carrier qualification trials were carried out at the same time the new bomber was flying its first combat missions in China in the spring of 1938. Armed with bombs, the B5N1 was used as a single-engined level bomber, in a fashion similar to a twin-engined machine.
(B5N2) Three-seat carrier-based torpedo-bomber
* B5N2 Model 12, or Type 97 Carrier Attack Bomber Model 12
* Twin 7.7 mm machine-guns, manually-aimed, in rear cockpit
* Fuselage rack for one 800 kg (18-inch) torpedo or three 250 kg bombs
* First flew in December 1939
* By the time of the Pearl Harbor attack, the B5N2 had totally replaced the B5N1 in all front-line units, both land- and carrier-based. Commander Mitsuo Fuchida was the aerial commander for the Hawaiian Operation; he flew in a B5N2 as observer/bombardier, and was also lead bombardier of the
49 Kates used as level bombers in the first wave. All of the B5N2 level bombers carried a single 1,653-lb. bomb made from a remanufactured armor-piercing shell. The 40 planes earmarked for the actual torpedo attack were led by Lt. Cdr. Shigeharu Mutara.
* After Pearl Harbour, the Kate did most of its later combat flying from land installations, figuring prominently in the Solomons, Marianas, and Philippines campaigns. Its last carrier-based engagement was the Battle of the Philippine Sea in June 1944. Insufficient performance, and poor crew and fuel-tank protection, contributed to staggering losses in all these campaigns, and so the Kate was relegated to second line and training units by the end of 1944. But the B5N2 found a new lease on life because it still had excellent long range endurance; it was used for maritime reconnaissance and anti-submarine patrol, in areas where Allied fighters were unlikely to be encountered.
So historically, it appears that the Kate was used as both a torpedo bomber and as a level bomber. As a level bomber it should only be attacking shore/harbour-based targets, and as a torpedo bomber it should be attacking sea-based targets.
Even so, as the war progressed it was simply out-classed by Allied fighters and ship anti-air armament.
So Admiral DadMan I think you are correct: the kate should NOT be used as a level bomber when it attacks SEA-based targets, a mission for which it is wholly unsuited.
A Kate from the carrier Zuikaku leaving Pearl Harbor; Hickam Field lies below.
