Bombing of Telos IV

The Bombing of Telos IV was one of the first "battles" of the Jedi Civil War.

Saul Karath, a Republic hero of the Mandalorian Wars and commander of the Leviathan, defected to the Sith Empire in a shocking move. As his first action as the new commander of the Sith fleet, Karath led an attack on the relatively undefended world of Telos IV. Using security codes that he had stolen, Karath was able to bypass Republic defense systems and infiltrate Sith bombers into the Republic docks before any warning could be raised. In moments, half the Republic fleet docked at Telos was destroyed. This was only the vanguard of Karath's attack, and he soon arrived with the bulk of his fleet, the Leviathan at its head.

Karath demanded Telos' surrender. When it refused, Darth Malak gave the order to bombard the planet. The resulting attack was devastating. Millions were killed in the attack, and more died soon after due to medical supply shortages. A nearby Republic task force in which Carth Onasi was stationed arrived in the system shortly after, but by then it was too late. Karath and Malak left Telos' scarred surface as a warning to those who would stand against the Sith Empire.

Aftermath
The attack left Telos' environment devastated. The atmosphere degraded into acidic vapor and all plant and animal life on the surface was obliterated. After the end of the Jedi Civil War, the Republic decided to use Telos as a model for rebuilding worlds left dead in the wake of the war, and financed the Telosian Restoration Project and construction of Citadel Station to purify the atmosphere and rebuild the ecosystem.

Republic soldier Carth Onasi was one of many left emotionally scarred by the attack. His wife dead and son missing, Carth swore revenge on Karath, who had been not only a hero to him, but his personal mentor. He came to fulfill this vow three years later on the bridge of the Leviathan.

In 3,951 BBY, Kreia predicted of Telos that "complacent and peaceful, it shall forget the time that Saul Karath orbited it and brought fire to its skies."

Quotes
"It was always intended for the Jedi to retreat to Telos should Dantooine be attacked - taking all their lore with them. We could not allow the tragedy at Ossus to happen again."

- Atris

"Such an act marked Telos for destruction. It is why the Sith came here, though the fleet commanders did not know why. It is why Revan ordered its destruction to mark the beginning of the Jedi Civil War. It was a message that there would be no place for the Jedi to retreat, to hide."

- Kreia