The Grentra was a Tandaran warship in service in the mid-22nd century. It was one of the faster ships in the Tandaran fleet, and able to sustain warp factor 6.5 for brief periods. The Grentra was equipped to fire plasma bolts, and carried grapplers. (ENT - Rise of the Federation novel: A Choice of Futures)
On September 25, 2162, General Valk showed the Federation representative Admiral Jonathan Archer a recording of a seeming Suliban attack on Kemsar Colony in the Grentra's drab grey conference room. Archer and his aide, Lieutenant Travis Mayweather, convinced Valk that their ship, the Columbia-class starship USS Endeavour, would be able to track the raiders who had kidnapped the children from the colony to sell them into slavery. Valk accepted Archer's offer to stay aboard Endeavour.
On the second day of the mission, Endeavour and the Grentra cornered the raiders at the disreputable Qhembembem Outpost. The fake Suliban ships were destroyed but the children saved by Endeavour. Moreover, the attackers were identified as Malurians masquerading as Suliban to sow dispute between the Tandaran worlds and the fledgling Federation. (ENT - Rise of the Federation novel: A Choice of Futures)