This top-secret unit killed 5,428 and rescued 574 in WWII
The Office of Strategic Services Detachment 101 was a predominantly Army unit set up to conduct guerrilla operations in Burma during World War II. Originally ordered to conduct limited sabotage and reconnaissance missions, the unit grew to lead almost 10,000 local fighters that killed thousands of Japanese, rescued hundreds of Allied pilots, and enabled the success of Merrill's Marauders.
The Coordinator of Information, the organization that would soon morph into the Office of Strategic Services, created Detachment 101 on April 14, 1942, as a sabotage organization with no organized plan or mission.
But the head of the COI, famed "Wild" Bill Donovan, picked a wild Army Reserve officer and gave him broad authority to pick a team and proceed as he saw fit. Maj. Carl F. Eifler had originally joined the military as a child but was discharged in 1923 at the age of 17 when the military figured it out. He became a police officer, customs agent, and Army Reserve officer.
Army Lt. Gen. Joseph Stilwell ran the China-Burma-India theater of the war and was not keen on having Detachment 101 in his battlespace, but he accepted them, partially because he had known Eifler from a previous command. Stilwell tasked the Detachment with shutting down Japanese operations around a key airfield.
The detachment began by sabotaging infrastructure in the area. The first operation, three simultaneous strikes against key bridges, went badly as only one bridge was destroyed and the U.S. teams suffered casualties. The next two operations suffered from rushed planning and little reconnaissance and failed.
But Detachment 101 built relations with the local Kachin people who resented Japanese rule and the mission hit its stride. The American soldiers recruited, paid, and deployed forward with their Kachin Rangers. The Kachins were generally smaller than their American counterparts but were strong and knew the battlefield and jungles much better.
One of the Kachins' preferred methods for killing Japanese were to set up ambush areas. They planted improvised bamboo spikes known as pungyi sticks in the undergrowth and then carefully placed their weapons in concealment.
When the Japanese arrived, the Rangers would attack, forcing the Japanese to decide between taking heavy machine gun and rifle fire in the open or diving into the undergrowth where pungyi sticks awaited them.
Initially, there was a small number of U.S. personnel leading a small number of guerrillas, but as the mission became more successful it got better funding and drew more local recruits. One Catholic missionary, Father Dennis MacAllindon, could speak Kachin and helped the Americans recruit.
The joint U.S.-Kachin team branched out into rescuing downed air crews and providing target reconnaissance in the jungle. The Japanese had been careful to operate primarily underground or under dense canopy to prevent being targeted by the Army Air Forces.
So the Kachins carefully watched the Japanese and noted the locations of airfields, supply caches, headquarters, troop buildups, and other threats. American radio operators then relayed this targeting data to bomber units that would strike.
In once case, a Japanese force had hidden their planes in holes covered in sod at an old airbase, making it appear unused from the air. Detachment 101 sent a heads up to the rest of the Army and they bombed the whole thing into ancient history.
Detachment 101 grew to encompass almost 10,000 Americans and locals, still mostly Kachins. When the rest of the Army became serious about retaking sections of Burma, mostly to reopen routes into and out of China, Detachment 101 was a key part of the mission.
The famed Merrill's Marauders formed the core of Operation Galahad, but Kachin forces protected their flanks, guided patrols, and even helped move equipment by elephant.
The Kachin forces and the rest of Detachment 101 were eventually credited with the deaths of 5,428 Japanese troops and the rescue of 574 Allied airmen downed over the Japanese-held area.
But the real significance of Detachment 101 was its ability to force the Japanese out of areas or degrade their operations to the point of irrelevance.