As the Japanese swept across Asia in the early years of World War II, the retreating Allies looked for ways to keep up the fight. In Malaya and Burma, agents had been left behind to stir resistance behind enemy lines, building up anti-Japanese operations from the safety of the jungle. In China, the American Office of Strategic Services helped both Nationalists and Communists in resisting the Japanese.

In Malaya and Burma, the British "left behind" teams that often worked in small groups, using bombs, grenades, and guns to ambush Japanese supply trucks traveling through the jungle at night. An attack might last less than a minute, a sudden burst of violence meant as much to intimidate the Japanese as to do material harm, breed paranoia, and force them to behave more cautiously. The teams spent far more time trekking through the jungle to their targets than attacking them, but when they did strike, the shock value was impressive.

One of the most famous formations involved in this was Detachment 101, the creation of American General "Vinegar Joe" Stilwell. Led by Carl Eifler, operatives from Detachment 101 lived in the jungle, suffering through torrential rains, malaria, and supply shortages to carry out guerrilla warfare against the Japanese. They recruited local Kachin and Karen people to form a force of 10,000 fighters, and these rebels persistently harassed the Japanese, launching quick strikes before retreating into the jungle.

While the fighting on the Asian mainland is often overlooked in favor of other theaters, at the beginning of 1942, Japanese soldiers in the 15th Army invaded Burma and drove out the British forces in a state of disorder. In fact, it was a headlong retreat, and with the fall of Burma, the Japanese posed a threat to India itself. As Britain scrambled to rebuild its forces and morale to hold back the Japanese, one British officer, Orde Wingate, with considerable experience with irregular operations in the Middle East, formed a radical plan to disrupt the Japanese forces now at the gates of India. He advocated taking the fight to the enemy by using a relatively small group of highly trained soldiers to attack the vulnerable Japanese supply lines that extended precariously through the Burmese jungle.

The "Chindits" came about as a result of Wingate's idea. They were a British-trained force of British, Indian, and Gurkha soldiers designed to be employed on long-range offensive operations behind the lines of the Japanese. They were launched on two major campaigns, one in 1943 and one in 1944, and they fought in some of the most brutal and grueling terrain and climatic environments on the planet. In addition to facing enemy fire, soldiers in Burma had to deal with monsoons, tropical diseases, thick jungles, bad water, and poor nutrition, along with hidden booby traps and the potential of being ambushed by local villagers. On top of all that, the Chindits were up against an experienced, tenacious, and savage enemy who rarely took prisoners.

Training for the operations was intense, fighting was fierce, and the casualties were high, which has ensured their service is still a subject of heated debate. The Chindits only conducted two significant operations in 1943 and 1944, and Wingate died in a plane crash in 1944 as the second operation was just underway, so many have argued that the casualties the Chindits suffered were excessively high for what was achieved. However, others argue that the Chindits played a vital role in disrupting both Japanese supplies and plans and made a significant contribution to India's defense. Perhaps the controversy was inevitable, because Wingate was undeniably a challenging personality who easily made enemies among his contemporaries, even as some begrudgingly considered him a military visionary.