Quirt, a Colonel, was the commanding officer of Quirt's prison ship, which functioned as an Imperial prisoner transport.
The ship was utilized by Quirt to collect lawbreakers on Formos and move them to the spice mines located on Kessel. During an attempt by the Millennium Falcon to flee Formos carrying a spice shipment, Quirt's ship intercepted it. Han Solo deceived Quirt, resulting in neither the spice nor the escaped Wookiee prisoner, Hronk, being discovered, and the Falcon was permitted to leave.