Attacker Four was the designation given to a Lioaoin cruiser by the Chiss Ascendancy. The heavy cruiser, along with three others, was sent to attack the Chiss warship Vigilant by the Lioaoin Regime, under orders from the Nikardun Destiny, when the Vigilant attempted to collect Senior Captain Mitth'raw'nuruodo from the Vak homeworld of Primea. Thrawn, aboard a commandeered Vak patrol boat, fired on Attacker Four, managing to cause significant damage while the Lioaoi were confused by the sight of a neutral Vak starship attacking. The Vigilant proceeded to escape in Four's shadow, preventing the other cruisers from firing.