The local history office in Nanjing, Jiangsu province, confirmed on Tuesday the date of the Soviet Volunteer Group's first combat in China during the War of Resistance against Japanese Aggression (1937-45).

According to the office, the combat took place on Nov 22, 1937, which differs from some previous Chinese and Soviet historical material.

Hu Zhuoran, a researcher at the office, said the date was confirmed after it scrutinized material from China, the United States, Japan and countries from the former Soviet Union.

"Based on pilots' memories, the Soviet historical material recorded that the first combat took place on Nov 21," said Hu. "Maybe the pilots did not remember correctly after many years passed."

"Because of weather conditions, the Japanese bombers were unable to take off. The first Japanese bomber flew to Nanjing on Nov 22. China's central news agency at the time also reported news about the combat on Nov 22," Hu said.

According to Hu, a reporter for Japan's Asahi Shimbun in Shanghai noted that the rain stopped on Nov 22, and Japanese naval aviators engaged in combat with bombers of a type "never seen before" over Nanjing.

A telegraph message sent by the Japanese navy's Second United Air Force Squadron at 7 pm on Nov 22 showed that a bomber was chased by the enemy, and some combatants were missing.

A reporter for The New York Times in Nanjing wrote an article on Nov 22 that was published the next day saying that an aircraft was damaged during combat and landed at what was then the Central Martial Arts Academy in Nanjing.

On Aug 21, 1937, China and the Soviet Union signed a nonaggression pact, and in late October, Soviet aircraft began to arrive in Northwest China to engage the Japanese army.

Because of the ostensible neutral status of the Soviet Union, no formal combat records of Soviet pilots were kept. So the date of the pilots' first combat remained unverified for years.

A collection of material in 2005 concerning the Nanjing Massacre showed combat took place on Dec 1, which delayed the arrival of the Japanese for about 10 days, according to Jing Shenghong, a history professor at Nanjing Normal University. "The confirmation of the date corrects mistakes in the Chinese historical material and is of important value," Jing said.

Contact the writer at cangwei@chinadaily.com.cn