[citation needed] Its strategic location across the Korean border allowed guerilla fighters to launch effective raids on Japanese consular police stations and then to retreat to the Chinese side of the boundary.
Additionally, the Northern Route Military Headquarters was established under the leadership of So Il, with Kim Chwajin commanding more than four hundred independence fighters at its officer training school.
To try to suppress those movements, he ordered numerous illegal police raids on suspected radical Jiandao base camps, which were protested by local Chinese leaders.
"[7] It is difficult for historians to determine who was behind the attack or whether the incident actually took place, the controversial event is historically significant because Japan used it to justify its escalated military intervention in Manchuria.
[citation needed] In reaction to the Hunchun incident, the Japanese punitive Jiandao Expedition was accordingly sent to Manchuria, and used search-and-destroy patrols to suppress the guerrilla fighters by carrying out numerous arrests and executions.
"[8] Korean independence forces in Manchuria were never effectively organized under the leadership of the Shanghai Provisional Government, but they achieved notable military victories against the Japanese brigades.
[11] In early 1921, after a series of skirmishes and retreats on both sides, as well as criticism from local Chinese authorities and the international community, most members of the 19th Division withdrew from eastern Manchuria.