This wartime map of India can be found in the archives of the American Geographical Society.
The AGS is a body of geographers proper founded in 1851, as opposed to the better-known National Geographic Society (f. 1888) which exists to “increase and diffuse” geographic knowledge.
The American Geographical Society and its capacious archive — at one point believed to be the largest map collection in the world — formerly lived at Audubon Terrace in New York. Since 1978 its map collection has been housed on the campus of the University of Wisconsin at Milwaukee, while the Society’s offices are in Midtown.