BEIJING, Sept. 13 -- China on Saturday released documents on a series of battles against the Japanese army in north China in 1939 as the country marks the 69th anniversary of the victory against Japanese aggressors.

This is the 20th part in a series of documents released daily by the State Archives Administration starting Aug. 25.

In October 1939, about 20,000 Japanese troops initiated attacks on the Shanxi-Chahaer-Hebei Border Region, a guerilla war area controlled by Communist Party of China forces.

The invaders encountered fierce resistance from the Chinese army, which rallied a total of 108 attacks, including guerrilla combat, to exhaust and wipe out the enemy, according to the archives.

The battles lasted for 43 days, resulting in more than 3,600 casualties of Japanese troops.

Norman Bethune, a Canadian doctor well known for his efforts to save Chinese soldiers' lives during the war against Japanese aggression, died from blood poisoning during the battles.

China has officially designated Sept. 3 as Victory Day to mark Japan's surrender on Sept. 2, 1945.