I'm not so sure the Japanese had better equipment at the start of WWII. The Zero was about the only thing that was qualitatively better than American planes, bu

I'm not so sure the Japanese had better equipment at the start of WWII. The Zero was about the only thing that was qualitatively better than American planes, but that was more due to them having optimized it perfectly for their doctrine. Once Americans developed tactics to counter the Zero, like the Thatch Weave, the Zero's relative performance went down significantly. However, Imperial Japan certainly had much more experience than the US at the start of the war: they'd been fighting in China for years, had carrier operations down to a science, and had dominated southeast Asia for even longer. But they ultimately failed to adapt as the war went on. In a way, America starting as the underdog actually helped long term: while the US kept improving equipment, incorporating what doctrine and training worked, and refining production processes, the Japanese military essentially continued to use what had worked for the relatively low intensity war they had been fighting before. The most famous example is probably that Axis (Japanese and German) pilots often had dozens of air to air victories, while the US sent their pilots home to train new pilots regularly. While the Japanese aces were formidable, the rest of their pilots weren't so great, and after so many pilots were lost there was nobody to create new good pilots. Over China, where the Zero was technically better than anything it went up against, it was fine to throw new pilots on missions with little experience, since the plane would compensate for inexperience. Against the US Navy though, even the most green pilot had trained from an experienced pilot and knew all the tricks and tactics that would otherwise take several combat sorties to discover. In short, the US pilots had lower peaks than the Japanese, but the baseline level was much higher. Another example is the Bofors 40mm antiaircraft gun. Reportedly the original Swedish blueprints had so many sections marked "machine to fit" that an engineer said that "the Bofors gun had been designed so as to eliminate the unemployment problems of the Great Depression"[0]. By the end of the war, production time of the gun had been cut in half, enabling every ship in the fleet to be loaded with ever increasing numbers of guns. Meanwhile, the Zero's factory didn't even have an airstrip, and it had to be carried disassembled on animal-drawn carriage to the nearest airport, up to the end of the war. TL;DR the Japanese didn't have better equipment at the start of the war, but they did have more experience. However, they relied on their tried-and-true methods of production and training, which were geared towards a lower intensity war against an inferior opponent in China. The US knew they started from the underdog position and worked from the start to improve everything everywhere, and continued to do so up until the end of the war. [0] http://www.navweaps.com/Weapons/WNUS_4cm-56_mk12.php#Use_by_USA http://www.navweaps.com/Weapons/WNUS_4cm-56_mk12.php#Use_by_...