<P> Underwater warfare was especially dangerous; of the 16,000 Americans who went out on patrol, 3,500 (22%) never returned, the highest casualty rate of any American force in World War II . The Joint Army--Navy Assessment Committee assessed US submarine credits . The Japanese losses, 130 submarines in all, were higher . </P> <P> In mid-1944 Japan mobilized over 500,000 men and launched a massive operation across China under the code name Operation Ichi - Go, their largest offensive of World War II, with the goal of connecting Japanese - controlled territory in China and French Indochina and capturing airbases in southeastern China where American bombers were based . During this time, about 250,000 newly American - trained Chinese troops under Joseph Stilwell and Chinese expeditionary force were forcibly locked in the Burmese theater by the terms of the Lend - Lease Agreement . Though Japan suffered about 100,000 casualties, these attacks, the biggest in several years, gained much ground for Japan before Chinese forces stopped the incursions in Guangxi . Despite major tactical victories, the operation overall failed to provide Japan with any significant strategic gains . A great majority of the Chinese forces were able to retreat out of the area, and later come back to attack Japanese positions at the Battle of West Hunan . Japan was not any closer to defeating China after this operation, and the constant defeats the Japanese suffered in the Pacific meant that Japan never got the time and resources needed to achieve final victory over China . Operation Ichi - go created a great sense of social confusion in the areas of China that it affected . Chinese Communist guerrillas were able to exploit this confusion to gain influence and control of greater areas of the countryside in the aftermath of Ichi - go . </P> <P> After the Allied setbacks in 1943, the South East Asia command prepared to launch offensives into Burma on several fronts . In the first months of 1944, the Chinese and American troops of the Northern Combat Area Command (NCAC), commanded by the American Joseph Stilwell, began extending the Ledo Road from India into northern Burma, while the XV Corps began an advance along the coast in Arakan Province . In February 1944 the Japanese mounted a local counter-attack in Arakan . After early Japanese success, this counter-attack was defeated when the Indian divisions of XV Corps stood firm, relying on aircraft to drop supplies to isolated forward units until reserve divisions could relieve them . </P> <P> The Japanese responded to the Allied attacks by launching an offensive of their own into India in the middle of March, across the mountainous and densely forested frontier . This attack, codenamed Operation U-Go, was advocated by Lieutenant General Renya Mutaguchi, the recently promoted commander of the Japanese Fifteenth Army; Imperial General Headquarters permitted it to proceed, despite misgivings at several intervening headquarters . Although several units of the British Fourteenth Army had to fight their way out of encirclement, by early April they had concentrated around Imphal in Manipur state . A Japanese division which had advanced to Kohima in Nagaland cut the main road to Imphal, but failed to capture the whole of the defences at Kohima . During April, the Japanese attacks against Imphal failed, while fresh Allied formations drove the Japanese from the positions they had captured at Kohima . </P>

Where the first war in the pacific occurred