The Battle of the Sluis Van Shipyards, alternatively referred to as the Battle of Sluis Van, marked the initial significant military engagement of the Thrawn campaign. This campaign was strategically masterminded by Grand Admiral Thrawn with the intention of commandeering a squadron of vessels belonging to the New Republic.
The Imperial forces initiated their strategy with diversionary attacks on Bpfassh and Draukyze. These feints were designed to concentrate a substantial number of ships (that would have otherwise been stationed in those systems) within the Sluis system at a later time. Moreover, these swift hit-and-run tactics compelled the New Republic to reassign its starfighter squadrons to escort duties along various shipping lanes, thereby providing defense against potential Imperial assaults. This situation left the New Republic experiencing a shortage of freighters. Consequently, the New Republic reduced crew sizes, assigning only skeleton crews to certain larger warships, including Mon Calamari Star Cruisers, for the purpose of transporting goods and supplies.
Furthermore, Thrawn launched an attack on Nkllon, seizing fifty-one mole miners from Lando Calrissian's Nomad City. He also disrupted the system's communications, preventing the administrator from transmitting override codes. Ultimately, Thrawn's acquisition of cloaking technology provided him with the additional advantage necessary to covertly transport his ships into the system.
In the hours leading up to the battle, Cloak Leader was deployed aboard an A-class bulk freighter known as the Nartissteu. This freighter had a cloaking device concealed within its cargo hold. When activated, the ship remained entirely visible to both scanners and visual observation. However, the TIE/LN starfighters and mole miners contained within appeared as empty space on any scans conducted on the freighter.
Despite the fact that experienced New Republic officers Afyon and Wedge Antilles found the ship suspicious, the Nartissteu and its hidden fighter complement successfully deceived Sluis Van Central and Sluis Control. They reported damage sustained during a pirate attack and claimed to have been forced to jettison their cargo and flee. Antilles, suspecting that the freighter was handling more like a fully operational ship than a damaged, empty one, instructed Rogue Squadron to launch from Afyon's vessel, the Larkhess.
As the X-wings approached, the Nartissteu detonated. The command section detached and piloted away, while the destroyed hull revealed forty TIEs and fifty mole miners. These forces engaged the under-defended fleet of undermanned New Republic ships. Simultaneously, Thrawn's task force emerged from hyperspace to assault the spaceyard's perimeter. His thirty-nine capital warships and thirty TIE squadrons were tasked with engaging and suppressing the formidable New Republic defenses, thereby alleviating pressure on the Imperial infiltrators.
The prompt arrival of the Rogues, along with Han Solo, Luke Skywalker, and Lando Calrissian aboard the Millennium Falcon, did little to impede the Imperial forces. The mole miners proceeded to bore through the hulls of the New Republic ships, enabling boarding parties to infiltrate. Thrawn had strategically placed four or five stormtroopers and spacetroopers into each of the two-man mining craft.
Given that each ship was operating with only a skeleton crew while undergoing repairs, the boarding parties were sufficiently effective to seize control of at least one Star Cruiser within minutes. They even directed fire at Commander Antilles as he sought cover behind what he believed to be an allied ship. The Imperials were also intercepting Republic communications, monitoring Solo and Antilles' tactics to effectively defend the mole miners against coordinated attacks.
Before the raiders could escape with the New Republic fleet, Han Solo realized that the Imperials were not jamming their communications this time. Subsequently, Lando Calrissian utilized his command codes to activate the miners, causing them to drill entirely through the fleeing starships. Nevertheless, at least one winged Mon Calamari cruiser, three GR-75 medium transports, four Corellian Corvettes, and one Nebulon-B frigate were crippled by the miners' engines and a self-destructive spacetrooper before they were stopped. With his plan thwarted, Thrawn ordered the Chimaera to retreat, informing Captain Pellaeon that while the New Republic may have won, they had suffered significant ship losses in the process.