C76 Water Sluice Floodgate Floodgate

Many people might not have heard the sirens in the military bases, but those friends in Nanjing could understand that every year, on the day of the Nanjing Massacre, there would be deafening air-defense sirens ringing in the streets and alleys.

The only difference between the sound of air-raid sirens and the sound of the siren was that the siren was always in a long, high-pitched state