IRW Praetus

The IRW Praetus was a Romulan starship, a bird-of-prey warbird, in Romulan Imperial Fleet service in the 2150s decade. (, "I.R.W. Praetus")

History
In the 2150s, the and the  were prototypes for a cloaking device designed for starships. 

In 2152, the two ships were patrolling cloaked minefields. ( "I.R.W. Praetus") At Unroth III, the pair of cloaked vessels made first contact with Humans and United Earth when the Earth Starfleet vessel Enterprise became stuck in the field. The Humans learned the name of the Romulan Star Empire, and departed with some hull damage from the mines. 

Unfortunately, the power requirements to cloak a ship were such that the Praetus and the Praetor Pontilus were unable to maintain their antimatter containment systems, and the prototypes were destroyed. 

After the loss of the prototypes, it would be over a century until the Romulans were finally able to develop and deploy a cloaking device capable of cloaking a starship.