How the WWII Burma Campaign Helped Turn the Tide Against Japan

The Burma campaign of 1944–45 was one of the decisive Allied victories of World War II. Fought in some of the world’s most punishing terrain, it helped keep China in the war against Japan by reopening an overland supply route, and it shattered the Japanese 15th Army, paving the way for the Allied reconquest of Burma (present-day Myanmar).

Japan had invaded China in 1931, but more than a decade later, it had still not conquered the country. A steady flow of American aid helped sustain Chinese resistance, making Burma, the gateway for those supplies, a critical battleground. “The Japanese had cut the overland supply to route to China known as the Burma Road,” says Robert Lyman, historian of the British Army and author of A War of Empires: Japan, India, Burma & Britain: 1941–45. “In 1944, the Allies were determined to reopen it.”

To that end, in 1944-45, the Allies launched a grueling campaign in Burma, waging war in the steep, jungle-covered foothills of the Himalayan mountains.

In 1944, the Allies saw victory in Burma as essential to the wider war against Japan. Getting supplies flowing again to China would help keep their forces in the fight, tying down a large part of Japan’s army. Additionally, it would support American plans to use Chinese bases for B-29 bombing raids against Japan.

Burma was also the gateway to British India, the crown jewel of the British Empire. Historians continue to debate how ambitious—or realistic—Japan’s plans for invading India were, but Japanese leaders hoped an invasion across the border might spark unrest against British rule.

Japan invaded Manchuria in 1931 and followed up with a full-scale invasion six years later. Seeking to dominate East Asia and build a self-sufficient, Japanese-led empire called the Greater East Asia Co-Prosperity Sphere, it expected a quick victory. Instead, the war dragged on.

To keep China in the fight, the U.S. decided to support Chiang Kai-shek’s nationalist government to provide a bulwark against Japanese expansionism. “Chiang Kai-shek … needed arms, ammunition, food and money from America,” says Lyman, “without which, he wouldn’t be able to continue to fight the Japanese.”

Most of those supplies reached China via Burma. They were unloaded at Rangoon (now Yangon) before traveling along the 717-mile Burma Road, a treacherous mountainous land route from Lashio to Kunming in China. “The aid meant the Japanese had more than half its soldiers tied down by the fighting in China and were losing large numbers of men,” Lyman says.

After attacking Pearl Harbor in December 1941, Japan rapidly conquered much of Southeast Asia. It invaded Burma in January 1942, captured Rangoon by March and cut the Burma Road, severing China’s main overland supply route. Within weeks, most of Burma was under Japanese control, and Japanese soldiers had reached the Indian border.

“It was a thrilling moment for [India’s] colonized peoples…who saw their white occupiers driven away,” says Phil Craig, historian and author of 1945: The Reckoning. “However, Japanese brutality would soon make many change their minds.”

The Allies responded by flying supplies over the Himalayas, on the perilous air route known as “the Hump,” and launching raids by British special forces called Chindits behind Japanese lines. They also started building a new road from India into Northern Burma that would connect with the old Burma Road. Fearing the Allies would reopen the supply route, Japanese Lieutenant General Mutaguchi invaded India in March 1944, setting the stage for the campaign’s decisive battles.

Mutaguchi’s plan was to attack the build-up of the British 14th Army at Imphal (a capital city in Northeast India, on the Burmese border), stop the Hump and prevent the reopening of the Burma Road. He hoped their actions might trigger an uprising against the Raj.

But his plan proved flawed. “Mutaguchi expected the British to collapse very quickly,” Lyman says. “But the British forces had been rebuilt under the command of General Bill Slim, one of the greatest British commanders of all time.”

Allied air superiority transformed the fighting. The Japanese fighters in Burma were no match for the Allies’ advanced Spitfire planes, which flew faster and higher and helped allow transport planes to continue their supply missions. Slim’s men learned to hold their ground, confident they could be resupplied by air while the increasingly isolated Japanese suffered in the jungle. “It was a big psychological reversal,” Craig says. Allied tanks also proved decisive, allowing Slim’s men to smash Japanese bunkers that had devastated the infantry.

While many members of the British 14th Army were African, nearly 85 percent were Indian. At Kohima, Mutaguchi discovered the mostly Indian defenders would neither retreat nor switch sides to the Indian National Army fighting alongside the Japanese. I have added this here, but it may not be necessary or breaks us narrative flow. Please delete if not needed!. Some 2,500 mostly Indian troops held off 15,000 Japanese in brutal, close-quarters fighting.

Their defiance meant that Mutaguchi would never capture the Allied supplies he had counted on and that the offensive would drag on into monsoon season. Trapped by deluges, many Japanese soldiers starved or succumbed to disease as they struggled to retreat through the muddy jungle. Depending on the account, 60 to 90 percent died.

“The invasion was a disaster for Mutaguchi,” Lyman says. “It was as decisive as Stalingrad in Europe’s Eastern Front, because it was a humiliating defeat, the invading army was destroyed, and the door was open for the reconquest of Burma.”

While British and Indian forces advanced in the south, American general Joseph “Vinegar Joe” Stilwell led a U.S.-Chinese force toward Myitkyina, a strategic Japanese-held town with an important railhead and the only all-weather airfield in the region.

In May 1944, an elite American infantry unit nicknamed Merrill’s Marauders along with Chinese soldiers captured the airfield quickly. But it took months of siege and fierce fighting until the Japanese abandoned the town, a crucial step toward reopening the Burma Road.

Early in 1945, Lyman explains, Slim realized that Japanese General Heitarō Kimura “wanted to fight around Mandalay, where [his forces were] strongest.” Instead, “Slim attacked where Kimura was weakest.”

He sent an armored thrust to seize the poorly defended but vital Japanese supply base and airstrips at Meiktila, around 80 miles behind enemy lines. The surprise attack forced Kimura to divert reinforcements from Mandalay, allowing Allied forces to capture the city after weeks of heavy fighting. The victory deprived the Japanese of their last major stronghold in central Burma.

Slim then turned to an unconventional tactic. Under the secret Operation Character, the British armed thousands of ethnic Karen guerrillas to harass retreating Japanese forces, disrupt their communications and gather intelligence. Lyman calls it “one of the most brilliant uses of special forces in WWII.”

Together, the victories at Meiktila and Mandalay, combined with the Karen campaign behind enemy lines, shattered what remained of Japan’s army in Burma. Rangoon fell to the Allies in May 1945.

For Craig, the Allied victory stemmed from Slim’s “fast thinking” and “new ideas.” Slim transformed the 14th Army into “a new high-tech army supplied by the factories of America and Britain that the Japanese couldn’t compete with.”

Lyman credits superior logistics, effective combined-arms tactics—in which aircraft, tanks, infantry and artillery worked in concert—and the performance of the Indian troops who made up the bulk of Slim’s army. Craig argues they remained committed, in part, because the increasingly Indian-led army had become an institution many hoped would serve a future independent India.

Even with the reopened supply route, American B-29 bombing raids launched from Chinese bases achieved “little success” before operations shifted to the Mariana Islands. But Lyman argues the campaign’s greater achievement was strategic: “Victory in Burma kept China in the war…[and] it punctured the myth of Japanese militarism because it was one of their greatest defeats.”