Sentinel-class landing craft
The Sentinel-class landing craft, also known as Sentinel-class shuttle, was a transport used by the Empire to carry troops, small vehicles and supplies.
After the Clone Wars the change was made from the starships that were able to land on planets to offload troops to spacebound Star Destroyers that brought troops into orbit but no farther, and the Galactic Empire needed a dedicated, armored, maneuverable landing craft to safely transport troops directly into battle. Sentinel-class landing craft was introduced before the Battle of Yavin and eventually became the main troop transport in the Imperial Navy. The Sentinel's primary use was to transport troops between Star Destroyers/Cruisers/Star Dreadnoughts and planets, but they could also serve as air support, short-range scouts, light cargo vessels and even starfighter support. The vehicle also made an excellent atmospheric transport and many Imperial garrisons had one of these vehicles. Several Sentinels were used on the desert world Tatooine, where they deployed sandtroopers and their dewback mounts to search for the missing Death Star plans.
Sentinels were also used in conjunction with larger Y-85 Titan dropships or AT-AT barges for joint infantry/armor assaults. However, because of their popularity, they were used by other groups including the Rebel Alliance, the New Republic, Galactic Federation of Free Alliances, mercenary groups, and the Imperial Remnant.
During the Galactic Civil War, the Rebels used a fleet of captured Sentinel landing craft as support ships. The Alliance logo was painted on their central wing, to help tell them apart from the Imperial ships. The New Republic also developed its own unique replacement for the Sentinel-class. The New Republic's Bantha-class assault shuttle featured much heavier armor than its Imperial counterpart.
Behind the Scenes
Several sources list the Sentinel-class as being 20 meters long, the same length as the Lambda-class shuttle. Based on the vessel's similarity to the Lambda-class and other craft in the same family (especially the Kappa-class shuttle), a more realistic length would fall somewhere between 29 and 45 meters. The space combat simulator Star Wars: X-wing Alliance, however, depicts the Sentinel at a length of 38 meters. A side-by-side comparison in the Star Wars: Empire at War terrain editor scales the Sentinel-class at approximately 31.6 meters. The scales from both Empire at War games, however, are known to be notoriously incorrect, especially the distortion between starfighters and capital ships. It is currently unknown which is the canon length.
The Sentinel is one of few C-canon elements to make it into the movies; it first appeared in the Shadows of the Empire game, and appeared in the special edition of A New Hope.