This was the Allied geographical codename rather than operational designation for Fort Hertz in the Kachin area of northern Burma (March 1942/1944).
Up to 1942 Fort Hertz had been maintained as an outpost of the Myitkyina Battalion of the Burma Frontier Force. During the Japanese 'B' (iii) invasion of Burma in 1942, a number of the British and Indian troops of the Burma garrison remained in the area, but the military authorities in India had no direct contact with Fort Hertz throughout most of the summer of 1942. Troops were finally parachuted into Upper Burma on 3 July 1942.
Under the command of Captain J. O. M. Roberts of the Indian 153rd (Gurkha) Parachute Battalion, this detachment had been ordered to investigate the state of the Myitkyina area and then march 150 miles (240 km) north to Fort Hertz. On 12 August 1942 Major Hopkins of the Indian 50th Parachute Brigade overflew Fort Hertz and discovered, somewhat unexpectedly, that it was in British hands. Roberts had reached the fort some days before. The landing strip was unusable, however, and on the following day a party, led by Captain G. E. C. Newland, of the Indian 153rd Parachute Battalion dropped into Fort Hertz with engineering supplies and by 20 August the airfield had been repaired enough that aircraft could land.
Lieutenant Colonel Gamble, the area’s new commander, arrived on that date, and was soon followed by a company of the 7/9th Jats. Roberts’s party was flown out at about the same time. Later during World War II Fort Hertz’s garrison, consisting of various battalions of the Indian army and the North Kachin Levies, formed an isolated northern post of the Allied armies engaged in the Burma campaign. With the assistance of Kachin irregulars, the route north from Japanese-held Burma to Fort Hertz was defended against a series of minor attacks in 1942 and 1943. In 1943 and 1944 the primary purpose of the men at Fort Hertz was the gathering of intelligence and the protection of the airstrip, which served as an emergency landing ground for aircraft flying the 'Hump' route between India to China over the eastern end of the Himalayas. This same airstrip was the only supply line for Fort Hertz.
Large-scale official training of the Kachin Levies did not start until August 1943, when a 'V' Force team arrived. A US advisory team of eight officers and 40 sergeants (radiomen, cryptographers and medical personnel) also flew into Fort Hertz. The US forces raised their own Kachin force, known as the Kachin Rangers, in the Myitkyina area during 1944.
When Lieutenant General Joseph S. Stilwell’s Chinese 'X' Force started its advance to cover the building of the Ledo Road and the operations of the US Northern Combat Area Command, the forces based at Fort Hertz advanced on Stilwell’s left flank and captured Sumprabum. They then continued their advance toward Myitkyina, capturing Taungup and eventually joining 'X' Force.