SEOUL, South Korea

HIS fatal mistake, the North Korean commando soon came to realize, was not killing the South Korean villagers when he had the chance. The orders were clear, if he and his fellow assassins came upon any civilians: kill them immediately, bury them and get on with the mission to slip into Seoul and kill the president.

But this was late January, the high-mountain ground was frozen, and Kim Shin-jo, a 27-year-old special forces lieutenant, did not want to go to the effort of digging graves. Instead he warned the villagers, encountered one night during the journey from the North, not to go to the authorities, after which he and his men continued on toward the Blue House, the presidential residence.

But the villagers ignored the warning and went straight to the police, who then alerted the military. “That was when it all began to unravel,” Mr. Kim said.

Dressed as South Korean soldiers, the 31 Communist commandos dodged their pursuers for three days, talked their way through various checkpoints and got to within a few hundred yards of the Blue House, where they were finally confronted. It was late morning, Jan. 21, 1968.