194165438+On February 7th, Japan attacked Pearl Harbor and the United States declared war on Japan. When the Pacific War broke out, because of military materials, the US government listed bristles and duck feathers as Class A strategic materials equal to arms, and promulgated the Regulation on the Control of Bristles. M5 1 ",which stipulates that all long bristles over three inches are supplied to the armed forces, and the consumption of people is strictly restricted. Folk (mainly paint industry) can only use mixed brushes (of which bristles are limited to 55%), and the manufacture of mixed brushes must be approved by the government and issued with certificates. Since then, the output of American brush factories has been greatly reduced, and many brush factories even use bristles processed by old brushes and dry brushes bonded with paint as raw materials.
To this end, the United States allows China Airlines to open the China-India route (that is, the hump route). It can fly the munitions of the US military stationed in China from Kolkata to Kunming or Yibin by American plane, and then transport the bristles back to China by return plane. The bristles were transported by Chennault's No.1 14 Air Force (the Flying Tigers). This route will fly over the Himalayan hump at an altitude of1more than 5,000 feet, which is twice as high as the usual flying height of the aircraft at that time, and it will often encounter violent airflow, which will cause the aircraft to break, and 45% of the aircraft will often break down. The United States is almost willing to trade the pilot's life for China's bristles.
During the nine years from 1937 to 1945, China's foreign exchange income from exporting bristles reached US$ 30 million.