Occupying  northeast China, Japanese planned to aggress the Soviet union. So, the Japanese supreme headquarters decided to set up three line of military bases along the area between China and Soviet union. The first line is the defense area. Series of forts are regarded as the base for Guangdong army to attack the Soviet Union and resist troops attack. The second line is rear military base, which is used to pursue the military action, build up or disperse the army. The third line is immigration development area. Usurping the China land to be cultivated, the Japanese want to make up the soldier resource and employ the veteran. This plan is the so-called North Development Plan of Guandong Army.

  In May 1934, the Guandong army started to build Hailaer fort in northeast China. It locates on the inner Mongolia municipality  hulunbeier prairie. After 4 years building, it was completed in 1937. Basing on the periphery high ground, Hailaer fort includes five main positions: Mongolian carin mountain, north mountain, south pine mountain, southeast mountain, east mountain and four auxiliary positions, accounting for 1 square kilometers. Each main position reinforced concrete blockhouses, the headquarters, the observation post, the artillery position. Most of positions were established on the highland, so they can support each other on firepower. Geography was considered. The wire netting was equipped, the landmine were installed in some land. Trenches were used.  Each one was five meters wide, and six meters deep. Antitank ditches and lots of antitank obstacles were constructed. Except the east mountain, the other four main positions have underground fortification, such as restroom, medical office, ware house, communication depot, kitchen, command headquarters, air vent and so on. Firebases mostly were connected to the underground fortification with the tunnels.

  Engineering of Hailaer is vast. The accurate number of Chinese laborers can not be determined. Considering the construction environment, the technical condition, the construction final years, the load of the laborers work, the illness and the dead of the laborers, alternatively labor, the quantity standard of each historical period structure, the experts infer that the fort had employed about 20000 laborers.

  Some laborers were deceived by the advertisement. Some are captured. They had to work more than ten hours a day without sufficient food and clothes. The laborers that died from tiredness and beat, or died of illness were transported by Japanese army trucks to the dene locating among the Mongolian cairn mountain and North mountain, to the north bank of Hailaer river and buried. When the project was finished, to keep secret, the Japanese army shot the laborers collectively by stages. The mass grave is the evidence that the Japanese imperialism aggressed China. The  testimony of the crime  can never disappear.

Part of Hailaer fort	Grave ruins of mass grave of Hailaer fort of Japanese