AN/SLQ-371 Bastille UDCL

The AN/SLQ-371 Bastille Universal Decoy and Countermeasure Launcher (UDCL) was the standard active defense system used by both UNSC Navy and CMA during the Insurrection and Human-Covenant War, and was also a common sight on some civilian vessels. Generally mounted in an all-encompassing array, they had six mortars organized into rows of three that fired rocket-propelled canisters in the path of incoming projectiles. They were capable of firing and reloading at astonishing speeds, however, the fixed vertical angles of their barrels limited their utility. A second-generation model further simplified their design and introduced adjustable elevation for the mortars.

The Bastille was originally loaded with semi-guided multispectral flares, active decoys, smoke canisters, and multiple varieties of chaff, where the full combination would deter most anti-ship missiles. Their long period of use saw the introduction of munitions to combat the Covenant, including electromagnetic missiles for countering plasma torpedoes, and even small short-ranged mines.

Following the Human-Covenant War, the AN/SLQ-371 Bastille was replaced by the AN/SLQ-492 Cyclone UDCL.