The Battle of U-WLT9 took place in the Stain region in early May 2017 between a Legacy Coalition fleet and RedSwarm Federation forces. Fighting took place over a valuable moon on which a TEST starbase had been anchored. Following a Stainwagon assault on the starbase, TEST Alliance deployed several force auxiliaries to repair the tower supported by separate fleets of Maelstrom battleships and Drake battlecruisers designed for burst damage at long range. Legacy forces were aided by a large number of carriers.

RedSwarm and Stainwagon Typhoon and Rattlesnake battleships opened fire around 17:26, suffering severe losses. Goonswarm Federation Cerberus heavy assault cruisers came to the aid of the friendly battleship fleet but were swiftly repelled by Lagacy Coalition forces. After realizing that they would suffer heavy losses at the hand of the Legacy Coalition battleship and battlecruiser fleets, the RedSwarm Rattlesnake fleet warped within range of the Legacy Coalition carrier detachment. The RedSwarm fleet did not break though the defenses of any TEST carriers due to force auxiliary presence, some of which were lost while in triage configuration.

A cynosural field was lit in proximity to the TEST carrier fleet around 17:47 and a number of RedSwarm dreadnoughts entered the fray at close range. Legacy Coalition responded immediately with dreadnoughts of their own which traded approximately equally with the hostile forces. Fighting turned to skirmishing around 17:53 when the last Stainwagon dreadnought had been destroyed and RedSwarm/Stainwagon forces retreated. Legacy Coalition retrieved the spoils of war in traditional fashion and later left the battlefield after successfully repairing the starbase.

Fighting in U-WLT9 was set to continue the next day but was cut short by the Stainwagon decision not to further pursue the destruction of the starbase.