In 4 ABY, the Interdictor Cruiser was deployed alongside the Imperial-class Star Destroyer Accuser in several patrol missions through the space around Endor. On one such patrol, the two warships were tasked with intercepting Agara, Fastooni, Tauuni, Tuana, and Triuna, all freighters carrying Bothan spies who were attempting to return to the Rebel Alliance Fleet from the construction site of the second Death Star.
The Grappler was driven off by a flight of Gold Squadron X-wings staging from the cruiser Liberty. After her gravity well was shut down to permit the cruiser's escape, the Bothan freighters also made the jump to lightspeed.
The Grappler was also an Interdictor in the service of the traitorous Grand Admiral Zaarin. This version is unlikely to be the same ship; the naming conflict could be a result of either this or the above mentioned Grappler having been constructed after Zaarin attempted his coup. Zaarin's Grappler was destroyed by forces led by Maarek Stele during a failed attempt to trap Thrawn on board the Victory I-class Star Destroyer Sceltor.