"The battle was a master class in tactical synergy," 63-year-old Zhao Yushun says.

For the volunteer guide, the Battle of Xinkou is more than a historical event, it's part of his family legacy. Zhao's grandmother, Liu Huan'e, risked her life as an underground informant for the Eighth Route Army led by the Communist Party of China. "Her defiance against Japanese brutality inspired my father, a soldier, and later, me," he adds.

Over two decades, he has collected artifacts and oral accounts to preserve stories of the battle, where the Chinese people united to resist the invaders.