South Korean White Horse and Tiger Divisions...

These units served in Vietnam and garnered a reputation as some of the toughest fighters in the field. One of my co-workers served with a South Korean outfit in Vietnam. He said they were polite to a fault, and some really bad-dudes when the lead started flying. They were tough soldiers, trained hard, and physical attitude-adjustment was quite common within the ranks.
The VC quickly learned not to harass a White Horse or Tiger Division outpost. The story is related of a mortar attack one night on a South Korean firebase. The Koreans went out in search of the mortar, and came back with a mortar-tube, base-plate, mortar rounds... and the heads of the VC mortar-team.
The was never any harrassing fire directed onto the South Koreans after this incident.

Tim