The Rescue on Myrkr took place during Thrawn campaign. The New Republic and Talon Karrde's Smugglers became briefly allied to defeat Grand Admiral Thrawn's forces on Myrkr. Luke Skywalker, Han Solo and Mara Jade were successfully rescued but the smugglers became unwillingly engaged in the war.
In 9 ABY, Myrkr was located between Imperial and New Republic territory. During that time, Talon Karrde's organization had its main base on Myrkr. In the early phases of Grand Admiral Thrawn's campaign, Imperial forces moved on the world in order to secure supplies of ysalamiri.
After being contacted by Joruus C'baoth, Luke Skywalker went to the Jomark system where he was attacked by the Chimaera. He escaped but was captured by Talon Karrde and his smugglers. He was sent to Karrde's base on Myrkr but eventually escaped the base in a Skipray Blastboat. He was pursued by Mara Jade in the Great Northern Forest.
Meanwhile, Imperial forces had arrived in Talon Karrde's base and discovered the presence of Skywalker on the planet.
After the crash of their Skipray, the Jedi was captured by Mara Jade. They latter tried to go out the forest but both were attacked and captured by Thrawn's forces. They were conducted to Hyllyard City where they was rescued by Lando Calrissian and Karrde's smugglers.
By shooting on Imperial forces and helping the former rebels, Karrde's smugglers had became enemies of the Empire. They were forced to evacuate Myrkr to Rishi. Consequently, Thrawn was free to settle on Myrkr to capture all the ysalamiri he needeed.