By 2364 he had risen to be Chancellor of Tigan and broke Tigan's traditional isolationist stance and opened up communications with the Federation. Shortly after the USS Enterprise-D arrived eager to engage with the Tigan and Lomac welcomed them via comm channels.
However minutes later when an away team arrived on the planet the Chancellor was a woman named Kadec. As the away team had beamed down, Kadec and her fellow conspirator Edic had used a gravimetric pulse to wipe parts of the Tigan central computer and remove Lomac's position as chancellor from history. The changes were instantly rewritten in the minds of the Tigan population via the Tigan interface, a network of cybernetic implants which automatically inform all Tigan of the latest information on the central computer.
Lomac unaware of his erased past found himself working as a security guard in the central computer building and lead a team which attacked and captured the Enterprise away team. (TNG comic: "History Lesson")