During the resistance against US sabotage of the North (1965-1972), especially during the 12 days and nights of battle in 1972, the "Air Defense Alarm" contributed to our people's overall victory. Timely alarms helped people be safe in factories and homes and helped avoid loss of life when enemy aircraft attacked. Those who had experienced this war period, when sirens and loudspeakers announced, "Pay attention!... Compatriots pay attention!... Enemy aircraft are ... km away from Hanoi..." always bring back the memories of fierce bombing.
At that time, Hanoi had an air defense system installed throughout the city with large and small loudspeakers to help the alarms be timely. When there were communications that the US aircraft were coming, the commander would be responsible for pushing the siren alarm button in the General Staff bunker to sound the sirens. After receiving the signal, 15 sirens would simultaneously sound. Hanoi Museum currently preserves one of the fifteen sirens.
It is a siren manufactured by Hanoi Mechanical Factory. From its establishment in 1955 until 1958, the factory produced equipment for the war effort of our people, including the large-capacity siren, which consists of 8 loudspeakers. This product shows the creativity of mechanical engineers. The siren (112cm high and 182cm wide) has a sizeable 8-loudspeaker system that broadcasts in all directions. The loudspeakers are funnel-shaped (65cm long and 26cm in diameter) and rotate around a fixed shaft with ventilation grooves. The top central part has a conical cap (45cm high and 70cm diameter). The lower part has a motor. When the motor operates, it rotates the shaft, and the loudspeaker sound covers a large area of over 10 kilometers.
The siren was placed on the roof of the Hanoi Mechanical Factory. During the resistance against the US, sirens had a function to alert the people and workers to hide safely and the combat forces to be in a combat-ready position. In the peaceful post-war period, it was used to announce the end of the shift for factory workers. The siren has entered the memory of the people of Hanoi, a familiar sound for workers at the Hanoi Mechanical Factory and those who lived in the surrounding area. The artifact has partially rusted and been damaged over time.
In 2011, the Hanoi Mechanical Factory donated the siren to the Hanoi Museum to preserve, display, and promote its historical value. The artifact is typical of those artifacts that have been selected for permanent exhibition at the Hanoi Museum.
Phạm Thị Thịnh