Jack was born into a neo-Jesuit family on the Lyran world of Zaniah and was groomed from a young age to join the priesthood; however, he took a similarly regimented lifestyle but within the Star League Defense Force instead. He went to the Combat College on New Earth and graduated in 2747 in the top ten percent. Though his parents were both Hegemony natives, his father never took the time to file the papers to claim his children as natives of the Hegemony; because of this, Jack was turned down in his request to be assigned to a Royal regiment, instead he was assigned to the 326th BattleMech Division.
Jack Lucas would have retired as a Lieutenant General after serving in the force for thirty years while at peace. The Periphery Uprising changed that when many of the senior leaders of the SLDF were unprepared to wage a war against an enemy that spanned many systems and who wanted to murder them. In 2766, Jack was promoted to General of 3rd Army by General Aaron DeChavilier, who was keeping an eye on Jack ever since Operation PERSUASIVE FORCE. As commanding officer of 3rd Army, they began to be known for their unbridled aggression that they showed toward their enemies. During the uprising, 3rd Army was able to keep casualties low due to completing their campaigns faster than any other Star League Army.
During all of the fighting, Lucas kept up the facade of being always-capable and unperturbed during conflicts. The longer that he kept up the facade, the more he began to internalize the stress and exhaustion that came with leadership which wreaked havoc with his health. When Stefan Amaris began his coup, and when the realization of the atrocities committed by his forces came to light, Jack began to see the enemy on a level of subhuman. He turned a blind eye when his troops mistreated prisoners and on a few occasions, executed POWs. Lucas was eventually relieved of command by General Aleksandr Kerensky, who wanted the Third Army to have a fresh leader to help them get through the last hump of Operation LIBERATION. Lucas was officially assigned to the "Planning and Strategy" command.
Soon after Terra was liberated, Lucas retired from the army and moved to Errai. There he got into politics and used his reputation from the SLDF along with his personality to win governorship of the planet and start the rebuilding process.
With the looming war clouds of the Succession Wars, Jack reinvented himself for the final time. He followed the path that his father wanted for him and became a parish priest for the worlds of Errai and Northwind. He would die at the age of 106 after spending almost forty years as a reverend.
- Historical: Liberation of Terra Volume 2, p. 18-19 "Jack Lucas profile"
- Historical: Liberation of Terra Volume 2, p. 95 "Gold Coast"
- Historical: Liberation of Terra Volume 2, p. 95 "Confession"