The Japanese chose to invade China in 1937, well before the United States and Great Britain entered the conflict that would become World War II. As Japan’s advances effectively cut off sea and rail routes to the Chinese forces by 1940, this Army Map Service product clearly demonstrated to contemporary planners that the rugged geography of the Burma Road had suddenly become China’s primary logistical lifeline.

This important map and other cartographic tools like it also defined the geospatial challenges posed by this route to both transit and defense. Supplies shipped to the southern Burmese port of Rangoon moved north by rail to the central city of Lashio, where the road started. From there, its 717-mile track crossed the Burma-China border and traveled through cities such as Wanting and Paoshan, winding over peaks rising thousands of feet and river gorges descending nearly as deep. It ended in Yunnan province at Kunming, a strategic linchpin in the fight against Japan.

The road’s importance did not go unnoticed by the Japanese. After taking Indochina in 1941 and Malaya at the start of 1942, they set their sights on Burma. A swift invasion took Rangoon in March and much of the road later that spring. Japan eventually pushed Allied forces out of all but far northern Burma, and a blockade of the land route left air transport as the Allies’ only option. Sorties from India over “the Hump,” a wall of towering eastern Himalayan peaks, delivered some supplies, but aircraft and personnel shortages meant they could not keep up with China’s needs for food, fuel and weapons.

Working under British Admiral Lord Louis Mountbatten, the Supreme Allied Commander in the theater, U.S. Army Maj. Gen. Joseph Stilwell spearheaded efforts to reopen the land route to China. With Japan firmly in control of the Burma Road, focus shifted to the Ledo Road, an alternative route proposed to enter Burma from the north and reconnect with the old road near Wanting. This route avoided most of the Japanese-held territory, but still required the Allies to retake land in the northeast.

Stilwell’s 1944 campaigns did just that, recapturing the critical transport hub of Myitkyina while the British beat back a Japanese counteroffensive in the west. Meanwhile, a majority African-American contingent of engineers worked furiously to build the road itself. By January 1945, successful American-Chinese attacks on Bhamo and Namhkam linked the Ledo construction with the original road, and on January 27, the Allies restored the land link with China.

Some of NGA’s earliest predecessors contributed to the campaign. Aerial reconnaissance and the service branches’ photo interpreters gave Allied forces an edge in the difficult terrain, especially after they gained complete air superiority in mid-1944. On the mapping side, the Engineer Reproduction Plant operated an office in northern India, helping to print maps for in-theater use. In the final year of fighting, the Map Division of the Office of Strategic Services set up shop in Kunming, providing support at the terminus of the road.

Logistical challenges like those the Allies overcame in Burma persist today. New technology has helped matters, but supplying campaigns in contested theaters around the world remains no less difficult and no less important. In Burma and China, it took well-trained, battle-tested soldiers to put supplies to good use, but geospatial solutions to daunting logistical obstacles proved critical to the Allies’ defeat of Japan.