The IKS M'Char was a Klingon warship under Commander Kaybok that halted and tried to search Kasidy Yates's freighter near Deep Space Nine in 2372, until Sisko forced it to withdraw.
The M'Char appears in the Deep Space Nine episode The Way of the Warrior, as part of the large Klingon force that gathers at the station under General Martok. The Klingons claim to be protecting the Alpha Quadrant from changelings and begin stopping ships leaving Bajoran space.
When the M'Char detains the freighter Xhosa, Captain Sisko takes the Defiant out and tells Kaybok that he has no right to search vessels in Bajoran territory. Faced with the Defiant's weapons, Kaybok backs down and lets the freighter go.
Martok later arrives in Sisko's quarters and reports that Kaybok has been put to death for disobeying his orders, an early sign of how far the Klingons are prepared to go.