He was a grave keeper but ardently loved his country and home town.

His patriotism was displayed in leading the battle of sinking down the American warship, General Sherman, which was a modern vessel in those days.

The U.S. imperialists, who had long waited for a chance to invade Korea, sent the warship to it. The invaders sailed the ship up to Pyongyang along the River Taedong in August 1866, firing shells and bullets towards villages and plundering possessions.

Indignant at their atrocities, Kim Ung U called upon people to turn out in fighting battles against the invaders.

On the basis of analysis of the river stream highly affected by low tide and high tide and the fighting methods employed by the ancestors, he took out a tactic to sink down the ship by fire attack.

Under his command, the villagers in Mangyongdae, together with the inhabitants of the walled city of Pyongyang and the government troops, loaded a lot of small boats with firewood, tied them together. Then they set them on fire at a time of low tide and floated them down towards the aggressor ship, so that it was set on fire and sank with all hands into the river.

The battle demonstrated the stamina and will of the Korean nation that would show no mercy to any aggressors.