 During the planning for the invasion of South Korea in the years before the war , the North Korean leadership began to create large numbers of commando and special forces units to send south . These units subverted South Korean authority before and during the war with terror campaigns , sabotage and inducing rebellions in ROK military units . Hundreds of commandos were sent to South Korea in this fashion , and by the end of the war up to 3 @,@ 000 of them had been trained and armed . During this time , North Korean leadership also ordered the creation of large conventional units to act as advance forces for the actual invasion . The 766th Unit was formed in April 1949 at the Third Military Academy in Hoeryong , North Korea . The academy was specially designed to train commandos , and the 766th was originally designed to supervise North Korean light infantry ranger units . Over the next year , the 766th Unit received extensive training in unconventional warfare and amphibious warfare . During this time , the unit was expanded in size to 3 @,@ 000 men in six battalions . 
 During the planning for the invasion of South Korea in the years before the war , the North Korean leadership began to create large numbers of commando and special forces units to send south . These units subverted South Korean authority before and during the war with terror campaigns , sabotage and inducing rebellions in ROK military units . Hundreds of commandos <a href='uninflect' title='1'><mark>were</mark></a> sent to South Korea in this fashion , and by the end of the war up to 3 @,@ 000 of them <a href='been_done' title='2'><mark>had</mark></a> been trained and armed . During this time , North Korean leadership also ordered the creation of large conventional units to act as advance forces for the actual invasion . The 766th Unit was formed in April 1949 at the Third Military Academy in Hoeryong , North Korea . The academy was specially designed to train commandos , and the 766th was originally designed to supervise North Korean light infantry ranger units . Over the next year , the 766th Unit received extensive training in unconventional warfare and amphibious warfare . During this time , the unit was expanded in size to 3 @,@ 000 men in six battalions . 
Durin da planning for the invasion of South Korea in tdayears before the war , thdaorth Korean leadership began to create large numbers of commando and special forces units to send south . dese units subverted South Korean authority before and ddurinthe war with terror campaigns , sabotage and inducing rebellions in ROK military units . Hundreds of commandos was sent to South Korea in this fashion , and by thedad of the war up to 3 @,@ 000 of them done been trained and armed . During this time , North Korean leadership also ordered the creation of bigass conventional units to act as advance forces for the actual invasion . The dath Unit was formed in April 1949 at the Third Military Academy in Hoeryong , North Korea . The adaemy was specially designed to train commandos , and the 766th was originally designed to supervise North Korean light infantry ranger units . ova the next year , the 76da Unit received extensive training in unconventional warfare and amphibious warfare . During this time , the unidaas expanded in size to 3 @,@ 000 men in six battalions .