Top-secret military documents from World War II have revealed the depth and strength of the alliance between China and the United States against Imperial Japan, as well as joint efforts to rescue downed US pilots.

The cache of intelligence documents, detailing a number of daring missions, is on display at Jianchuan Museum in Anren, Sichuan province.

More than 1,100 documents and other artifacts were donated by the family of Major Richard Hill (1908-92), a US military intelligence officer who coordinated the rescue of 46 US pilots shot down over occupied China.