The Holan War and the Federation of Leto.

The Holan Cluster is a moderatley populated star cluster, which for millenia had been ruled by a monarch, until it joined the young Empire.  It suffered through a few years of violence between the monarchists and pro-Imperialists, then it settled down, the monarchists having been defeated.  There was peace for many decades, until suddenly the monarchists launched full scale assaults on Imperial Holan worlds, so the Empire commanded their two battalions into battle.  As the war between the Empire and the Holan monarchists raged on, a politician from Hola 4 appeared in the Senate named Leto.  Leto, a Kerronian, offered new policies in these troublesome times, and he ran for Chancellor of the Imperial Senate.  Just as he was going to win the election, Adas Ganjis, a human from the Alpha Centuri system, revealed Leto's true motives, so Leto fled from the capital and declared war on the Empire. The Imperial navy confronted Leto's private battalion outside Hola 2.  Leto's fleet was able to hold off the enemy navy long enough to reach the planet surface, they then barricaded themselves in Leto's fortress.  The Imperial army laid siege the fort for three weeks, they called on the help of the Burrus army, who successfully razed the fort.  Leto was exiled to the asteroid-world Krel, where he dug for ore for twenty years.  He died of Krajeck's Lung.  The Hola Cluster ceceeded from the Galactic Empire after the Leto Crisis, forming the Holan Independency.