Sentinel was an EF76 Nebulon-B escort frigate that saw action for the Imperial Navy throughout the duration of the Galactic Civil War.
The Sentinel received orders to intercept a Rebel assault targeting the Imperial surveillance satellite infrastructure situated close to Coruscant. Unfortunately, it did not arrive in time to stop a solitary Rebel X-wing from obliterating both the satellites and the transports engaged in mining operations in that region.
Subsequently, the Sentinel was assigned to protect a supply depot located within the Hollan D1 sector. This depot was later assaulted by X-wings and Y-wings alongside the Mon Calamari Star Cruiser known as the Cathleen, prompting it to jump to hyperspace while being chased by the Cathleen.