The unit consisted of 31 civilian recruits, mostly petty criminals and unemployed youths, and underwent three years of harsh training on the island of Silmido.

Unit 124 was the only tier one special forces unit of the Korean People's Army Special Operations Forces (KPASOF) created specifically to assassinate Park Chung Hee in an operation to enter secretly across the Demilitarized Zone and kill him at his presidential residence, the Blue House, in Seoul to trigger political turmoil.

However, Unit 124 were detected by the police only 100 metres from the Blue House wearing Republic of Korea Army (ROKA) uniforms, and 29 of 31 commandos were killed or had committed suicide within a week.

A contemporary news report in The New York Times stated that 23 members of the unit, described by the Defense Minister Chung Rae-hyuk as "special criminals," had killed 12 Air Force guards on Silmido, escaped the island dressed as paratroopers, landed on a beach near Incheon around 1pm and then hijacked a bus.

One of the guards, Yang Dong-su, confirmed that the unit's mission had been to infiltrate North Korea and kill Kim Il Sung.

Yang also gave his version of why the uprising occurred: "They revolted because they felt that they were never going to get the chance to go to North Korea and that they would never be allowed to leave the island.