"Wolves and dogs barked outside Wanping City, and gunshots fired on Marco Polo Bridge." The poem describes the fierce war situation of Chinese soldiers fighting against Japanese aggression. The background of the story describing the situation is a heavy historical event of China's Anti-Japanese War. An indelible experience in China's past Anti-Japanese War, which was the starting point of the Chinese nation's all-out war of resistance, was called the "Marco Bridge Incident", referred to as the "77 Incident", outside Wanping City The "wolf dog" is a metaphor for the Japanese army that invaded China at that time. The Japanese army held a so-called military exercise and deliberately claimed that a Japanese soldier was missing and needed to search the city. When the Chinese soldiers refused, they took the opportunity to launch an attack from Wanping City to Marco Polo Bridge. "The gunshots were fired on the Marco Polo Bridge" reflected the tenacious resistance of the Chinese soldiers at that time.