When the war broke out, President Kim Il Sung set a task to move a munitions factory in Pyongyang to safe place as quickly as possible.

So, the workers of the factory moved its equipment and facilities to an underground tunnel in Kunja-ri to produce the weaponry.

In spite of the shortage of materials and manpower, and difficult working conditions, they launched a drive for increased production in the indomitable fighting spirit under such slogans as "Let us thoroughly implement the instructions of Supreme Commander General Kim Il Sung!" and "All to the final decisive battle for victory in the war!".

During the strategic temporary retreat, a death-defying corps organized with 20 workers of the factory produced 750 stands of submachine guns in six days by turning the belt of lathe with hands.

Whenever electricity was cut off due to the enemy's bombing, they would process the accessories with torches in their hands, never stopping their work.

They continued to work without rest and eating uncrushed maize and salt to produce grenades. They also turned out weapons by recycling worn-out bearings and by use of domestic timber, breaking the custom that gunstock could be made only with white birch.

In the course, there emerged multi-machine tenders and persons who over-fulfilled their assignments at 500 percent. Even a woman worker set a record of filling 600 boxes with bullets in one shift.

In this way, the workers of the Kunja-ri underground arsenal drastically increased the production of weaponry such as submachine-guns, mortars, bullets and grenades for the great victory in the war.