China on Friday unveiled a trove of previously unseen materials detailing the Japanese Imperial Army’s wartime biological-weapons program, deepening the documentary record of Unit 731’s activities in northeast China. The Exhibition Hall of Evidences of Crime Committed by Unit 731 in Harbin displayed 3,010 pages of archival documents, 194 minutes of video, 312 photographs, 12 postcards and eight letters. Curator Jin Chengmin said the collection, drawn from Japanese government archives, oral testimony from Unit 731 members and donations from Japanese citizens, further demonstrates that the germ-warfare campaign was a pre-meditated, state-run operation. Separately, the Guangdong Provincial Archives released photo collections and telegrams donated by Japanese historian Seiya Matsuno that chronicle atrocities committed by the Japanese Army’s 18th Division during its 1938-42 campaign in southern China. The materials include images of civilian resistance slogans and records of counterfeit-currency operations in Hong Kong. The disclosures come as China marks the 80th anniversary of Japan’s unconditional World War II surrender and the 40th anniversary of the Harbin exhibition hall, underscoring renewed efforts to document wartime crimes and preserve evidence for historical research.