Martians vs Tarkin

There has been a long-standing emnity between Martians and Tarkin. Mars was the first planet that the Tarkin invaded, and they were the first contact Martians had with an alien species (excluding the infamous human time-traveller who gave both planet and its native sapients their names three centuries earlier).   The Tarkin being a shape-shifting species, infiltrated Mars over the course of several decades before the invasion became public. This occurred earlier than they had planned, and war broke out. It ended in a stalemate, with Mars' resources depleted and both sides having suffered too many losses to continue. The authorities on Tark refused to back down and remove their people from the planet, resulting in the abandoned Tarkin having no choice but to settle on Mars in a very uneasy peace agreement.   Over the next century or so, the relationship between Martians and their cohabiting Tarkin went through varying amounts of tension, but no outright conflict. The Martians rebuilt, and after joining the Interplanetary Alliance, Mars grew in political and technological power to rival Tark. After a series of petty squabbles between the two planets, Mars launched a full-scale attack.   War between the two planets was devastating to the Tarkin community on Mars; there had always been a strong divide between those who felt that Mars--the only place they had ever known--was their home; and those who believed strongly that their loyalty should be to their ancestors' homeland. While Mars and Tark clashed, violence broke out between the two factions. More of the community were killed by each other than by hostile Martians.   Tark declared victory after fifty-two years of war. Their ships raided Mars and took all the Tarkin remaining there, regardless of whether or not they wanted to leave. They also took ten percent of the remaining Martian population. Both Martians and the Mars-born Tarkin were settled on Tark in designated settlements, where they and their descendents were treated as second-class citizens.   Tark's continued invasion of other planets eventually led them to Earth. The invasion strategy had been fine-tuned over the centuries, still relying on long-term infiltration of the native sapients by shape-shifting. This particular invasion was noteworthy for the leader of the advance guard being a Tarkin who was one-quarter Martian--a rarity in itself for obvious reasons, but completely unheard of in a position of authority.   The invasion of Earth came to a head during the Millenium Glitch, which erased the entire year from the memories of everyone on Earth regardless of species. As such, history cannot say exactly how it ended ...