Naval Anti-Aircraft Guns and Gunnery. Norman Friedman

for an aircraft capable of maintaining surveillance over Pearl Harbor, the US fleet base, from Japanese airfields. Such surveillance was necessary if, as the Japanese hoped, they could intercept and defeat the US fleet before it reached their home waters. The aircraft also had to be capable of carrying out attacks at long range. Yamamoto and others were interested in using a force of land-based bombers which could shuttle among the Micronesian islands Japan then ruled as League of Nations mandates. It was clear that the flying boats Japan was using at the time lacked the requisite performance.⁵ The requirement was in accord with the Japanese naval strategy of wearing down an approaching US fleet before it encountered the main Japanese fleet, and the high performance envisaged would give the new bomber a reasonable degree of immunity against the fleet’s fighters. Yamamoto chose Mitsubishi as sole-source developer because that company had imported engineers from the German company Junkers (which was building high-performance twin-engine bombers) specifically to obtain the technology involved. In effect ‘Nell’ was the air power equivalent of the Yamato class battleship: a technological solution to the numerical inferiority of the Japanese battle fleet. The ‘Nell’ entered production in June 1936. As the longest-range Japanese bomber, it participated in the war against China that began in 1937, first carrying out attacks from Formosa in August. These operations made the British aware of it, though not of its extraordinary range. It also appears that the British tended to mirror-image, and thus to associate all land-based bombers (such as G3M) with the Japanese army, not the navy. That may have blinded them to the threat of such aircraft (in 1942 US air intelligence was counting Japanese biplane torpedo bombers as the aircraft which sank the two British capital ships).

      The Heinkel He 111H-6 was the main German wartime land-based torpedo bomber, typically carrying two torpedoes (in this case practice F-5bs) as shown. Numbers were always limited, and it lacked radar. This aircraft was used mainly against Russian convoys, from 1942 onwards. (Philip Jarrett)

      The longest-ranged German anti-ship aircraft was the Fw 200 Condor, used both for direct attack and for reconnaissance in support of U-boats. (Philip Jarrett)

      Japanese land-based units (including seaplanes) were organised into Air Groups named after the cities at which they were based. In 1940 the Japanese created an 11th Air Fleet of medium bombers. It consisted of three Air Flotillas, each of which consisted of two or three Air Groups. In effect it was the land-based equivalent of the First Air Fleet, the carriers and their aircraft separate from the First Fleet (which included two carriers supporting the battleships directly). There were also fleets intended specifically to operate in the Mandated Islands: the Fourth and Fifth. Among their roles were attrition of any US force trying to pass through the Mandates en route to the expected decisive battle in home waters. Fourth Fleet included 24th Air Flotilla, equivalent to the three medium bomber flotillas (21st, 22nd, 23rd) of 11th Air Fleet. In addition to the attacks on the two British capital ships, aircraft of the 21st and 23rd Air Flotillas were responsible for the early attacks on the US air bases in the Philippines.

      The French Navy had both a few carrier aircraft and considerable numbers of land-based torpedo bombers as well as seaplanes. Its aircraft do not figure in this book because it had few opportunities for action before France fell in 1940.

      Before the war Germany had a separate naval air arm equipped with ship-based floatplanes and with larger He 115 coastal floatplanes and flying boats.⁶ Despite an agreement leaving attacks against ships to the naval air arm, the Luftwaffe created its own anti-ship unit, X Fliegerkorps, which soon absorbed the few land-based units the navy had formed. At the outbreak of war the Luftwaffe considered the torpedo inadequate compared to bombing, particularly dive or glide bombing. Torpedo attack was frowned upon as tactically difficult. In November 1940 Göring extracted from Hitler an order temporarily forbidding the provision of aerial torpedoes to anti-shipping units, in theory to allow their use in a special operation in the Mediterranean (this was soon after the Luftwaffe conducted successful torpedo trials using the He 111). The Luftwaffe did not take over development of air-launched torpedoes until 1942, by which time it was too late to develop new ones for wartime service. German aircraft were used most extensively against merchant ships between 1939 and 1941. According to a post-war study published in the BuAer Confidential Bulletin, during this period Allied losses in ships sunk, captured and severely damaged were about twice that the United States brought into the war in December 1941. In effect the 1939–41 German war on merchant shipping cost the Allies a year of new construction. Apart from mining, which peaked in November 1939, German aircraft did not attack merchant ships during 1939, due both to lack of resources and to deference to neutrals. Systematic attacks on minesweepers began in December, and attacks on merchant ships began with the invasion of the Low Countries in May 1940. During the thirteen months ending 31 May 1941, before German air assets were redirected against the Soviet Union, German aircraft sank or severely damaged 3.8 million tons of merchant ships, compared to 3.2 million for U-boats; the aircraft accounted for 1.7 million tons sunk and 2.1 million tons disabled.

      The Germans made extensive use of their longest-range aircraft, Fw 200 Condors (modified pre-war airliners), against merchant ships. Because they could not dive-bomb, like Ju 87s or glide-bomb like Ju 88s, Condors had to make masthead attacks in order to score hits. Before British and other merchant ships could be armed adequately, they were effective: the Germans claimed that in the initial campaign between 15 March and 31 October 1941, bomber attacks accounted for 161 merchant ships sunk (plus one probable) and 113 damaged. This was apart from bomber attacks around the British Isles. As the merchant ships were increasingly armed, these attacks had to be abandoned, initially against convoys and then even against individual ships. Eventually the Condor was modified to attack at high-level using a computing bomb sight. These aircraft were also used for aerial mining around the western ports of the United Kingdom, and eventually to launch stand-off missiles. Their most important role was reconnaissance in support of the U-boat campaign. Success was hampered by the inability of both the U-boats and the aircraft to find their positions accurately, so that a convoy position report might be useless (the wolf packs solved the problem by creating patrol lines of submarines, but that became impossible as Allied air cover improved). The reconnaissance role became crucial after mid-1943, when the Germans lost their ability to read convoy codes. Admiral Karl Dönitz began to seek air support for the U-boat campaign almost upon gaining office as naval chief early in 1943. In February 1943 he signed a memo: air reconnaissance was now crucial. Aircraft had to penetrate to mid-Atlantic, find convoys, shadow them, and lead U-boats to them, because the existing wolf pack tactics of contacting and shadowing convoys (coupled with code-breaking) were proving less and less successful. Reconnaissance was of limited value because aircraft lacked the endurance to search large areas well out in the Atlantic: they could only fly out to a chosen position and return. Without code-breaking, there were no designated convoy positions.

      According to the German navy, only in 1941 did the Luftwaffe began to accept that an anti-shipping campaign was the best weapon to use against the United Kingdom, and in the first quarter of that year it shifted its effort to attacks against British coastal targets and shipping west of Ireland. There was also a vigorous and effective aerial mining campaign. Aircraft and U-boats were integrated to an extent to oppose Allied convoys to the Soviet Union. The Germans claimed 25 per cent torpedo hits against convoys PQ16, PQ17 and PQ18. They found that it took far fewer torpedo sorties than dive bomber sorties to sink a ship: 9.8 vs 23.6 against PQ16 and 7 vs 9.2 against PQ17 (best weather for dive bombing), but 7.3 vs 24.3 against PQ18 (worst weather for dive bombing). After the war, German naval officers complained that even when they could be convinced to attack convoys, pilots generally concentrated on the larger ships, which they imagined were the more interesting targets, avoiding the escorts and the smaller, more vulnerable ships; large ones could absorb many hits without sinking.

      Like Germany, the United Kingdom had an independent air force, but it also had a Fleet Air Arm which reverted to Admiralty control in 1939. The RAF had long been interested