The historical event reflected in the slogan "Compatriots work together to save Qingdao" is A. September 18th Incident B. May 4th Movement C. July 7th Incident

The historical event reflected in the slogan "Compatriots work together to save Qingdao" is B. May Fourth Movement.

The May 4th Movement was a movement that took place in Beijing on May 4, 1919, mainly involving young students, with the participation of the general public, citizens, business people and other classes. Through demonstrations, marches, The origin of the patriotic movement, which took various forms such as petitions, strikes, and violent confrontations with the government, was that during the First World War, the European powers had no time to look east, and Japan took the opportunity to intensify its aggression against China, seriously damaging China's sovereignty.

In just two months, from the celebration of "Justice over Power" in November 1918 to the Paris Conference in January of the following year, China at that time fully demonstrated the principle of "a weak country has no diplomacy since ancient times". The law, the so-called "justice triumphs over might" is just a beautiful fairy tale. The May 4th Movement directly affected the birth and development of the Communist Party of China. The history of the Communist Party of China generally defines it as an "anti-imperialist and anti-feudal patriotic movement" and uses this movement as an example of the old democratic revolution and A watershed in the new democratic revolution.