Sladek was an Invid who lived in the years when his people waged a war against the Robotech Masters. By the time of the conquest of Tirol, he held the rank of Commander and was stationed in the garrison on the planet Karbarra. The native Karbarrans had been placed under Invid control and did not resist in fear of the fate of their children which the Invid held as hostages. In addition to Sladek, the garrison was commanded by an Invid Brain that controlled the Inorganics that made up much of the ground forces. When the Sentinels arrived, the Invid forces battled them and Sladek was informed by his subordinates of the presence of an unknown group near the Karbarran mines.