Originally posted at Edge of the American West.
On this day in history (Tokyo time), units of the Imperial Japanese Navy mounted an assault on the American naval base at Pearl Harbor. English language accounts of the attack, whether scholarly or popular, have focused on the American side of things, usually with a nod to Japanese treachery. But it is the Japanese side that is actually—in military terms—the more interesting. Like the Germans in 1940, the Japanese showed with devastating the effect the value of a new method of warfare. The attack on Pearl Harbor rewrote the doctrine on naval warfare, and much of the next three years consisted of both navies, Japanese and American, desperately deciphering the writing.
What was revolutionary was not the use of airpower. Or, to put it more accurately, it was not simply the use of airpower. Aircraft carriers had appeared in all the world’s navies in the interwar period and were now integral parts of the fleet. The short-ranged and slow planes flying off an aircraft carrier were, however, largely incapable of inflicting substantial damage on the main line of a battle fleet, Billy Mitchell, notwithstanding. Against the enormously thick armor of the battleships—designed to protect against shells coming in at supersonic speeds—the puny bombs carried by those aircraft did little damage. Thus, the aircraft carrier became an adjunct to the heavies, used for scouting and observation. The battle line charged forward while the aircraft carrier lurked in the background, a second-class citizen.
What changed in the run up to WWII was the pace of technological innovation and doctrinal experimentation. The basics of the aircraft carrier and been settled in the 1920s and remained similar throughout the war, changing only in size. But aircraft changed rapidly and dramatically in the 1930s, a pace that accelerated in the late 1930s. Planes went from being slow short-ranged biplanes to fast long-ranged mono-wings. Plane generations shifted from year to year, and a plane that was cutting-edge one year might be obsolescent the next. The two navies which took the greatest advantage of this were the American and Japanese. Both, surrounded by massive oceans, had a vested interest in naval excellence, and both worked feverishly to figure out how to use these new weapons.
As a result, doctrine sped along with technology. The challenge was to deliver massive amounts of ordnance at extended range against armored, maneuvering ships which, annoyingly, would shoot back. The settled result in both navies was the creation of three kinds of aircraft: dive-bombers, torpedo planes, and fighter escorts. The first, dive-bombers, would attack from high in the sky diving towards the target and releasing the bomb at the last moment before pulling up. Torpedo planes, on the other hand, would attack from low, angling towards their target and releasing a torpedo which would drive the rest of the way in and hit the ship. Fighter escorts would protect the first two groups on their way to the target and as they attacked.
That was the theory. In practice, it proved enormously difficult for either dive bombers or torpedo planes to find or hit their targets. The Pacific was a big ocean and fleets—no matter how large—were an infinitesimal part of it. Even if found. warships did not *want* to be hit, and did everything they could to avoid it. They shot at the planes. They twisted and turned to avoid the bombs and torpedoes. They launched fighters to counterattack. They sailed into rain squalls. They kept their lights off at night. All of these things meant that the attacking aircraft usually scored an extremely low percentage of hits. Later in the war, at Midway, American planes mounted hundreds of attacks on the Japanese fleet and scored fewer than ten direct hits (all bombs, no torpedos). And Midway was an overwhelming American triumph.
In planes and aerial doctrine, then, both the Japanese and American Navies were similar. Neither had an enormous advantage in plane technology overall. The Japanese torpedo bombers, the Nakajima B5N (“Kate” its US identifier) was better than the American Douglas TBD Devastator. The torpedo it dropped was *much* better. The American Douglas SBD Dauntless was a better plane than its Japanese counterpart, the Aichi D3A (“Val”). The fighter escorts on each side were so different as to be nearly uncomparable. The Japanese Mitsubishi A6M (“Zeke”, though better known as the “Zero”) was a lightweight, highly maneuverable, long ranged fighter plane that achieved those qualities by sacrificing any armor protection at all, either for pilot or plane. The American Grumman F4F Wildcat was not particularly maneuverable, rather short-ranged, and pretty heavy, but its toughness and heavy armament were legendary. Whereas Zeros tended to dissolve into flames under fire, the stories of Wildcats making it home after being hit by hundreds if not thousands of rounds of ammunition are too many to recount.
Where the Japanese surpassed the Americans was not in their use of the planes but in their use of the carriers. Whereas the American carriers were deployed singly, as part of a larger squadron including battleships, the Japanese put their carriers together—for the most important missions—as a single large striking force. Early in 1941, Admiral Isoroku Yamamoto, the commander-in-chief of the Japanese Navy, organized the First Air Fleet, consisting of all of Japan’s carriers. The First Air Fleet, and most particularly the six heavy carriers composing the Kido Butai, or Mobile Striking Force, would be the hammer of the fleet. Off their decks could fly more than 300 warplanes, a larger number than that of any other fleet in the world. What they could not achieve in individual accuracy, the Japanese aimed to make up in numbers.
It was this fleet that sailed to attack Pearl Harbor. A British attack on the Italian fleet at Taranto in 1940 had suggested to the Japanese that such an assault was possible. The reasons leading to the attack, and the events of the attack itself, have been detailed innumerable times. For the purposes of this post, however, the critical thing is that the new Japanese doctrine worked well. The 353 aircraft launched from the decks of Kido Butai savaged not only the fleet at anchor in Pearl, but also the aircraft and equipment ashore. It was perhaps the easiest possible target: a naval base taken by surprise, with ships at anchor, boilers dark. Having said that, even such an overwhelming assault failed to destroy critical parts of the base: the American submarine pens, the fuel oil farm, and, most critically, the American aircraft carriers. Such was the inefficiency of air attack in 1941.
It was, nonetheless, a spectacular success for the Japanese. They had demonstrated to themselves and to the world the effectiveness of concentrated naval airpower. Kido Butai would roam the Pacific over the next six months, hammering target after target and ranging as far as Sri Lanka in the Indian Ocean and Australia in the southern Pacific. But the Americans were fast learners and in this new naval doctrine loomed the seeds of Japanese defeat. If the benefit lay not in who could amass an extra ship or two, but an extra fleet or two, then the Americans had a decisive advantage,
not only in the production of carriers and planes (24 American vs. 16 Japanese during WWII) or planes (over 300,000 for the U.S. vs. 75,000 for the Japanese) but in the industrialization of pilot training (several hundred thousand vs. 15-20,000). By 1945, the “Murderer’s Row” of the American 3rd and 5th Fleets, with 8-10 carriers and over 500 planes, roamed the Pacific, hammering the Japanese as Pearl Harbor had been hammered. The six carriers of Kido Butai did not live to see that day.