Hosnian Cataclysm

"Today is the end of the Federation! The end of a government that is weak!. At this very moment in the Sol system, a system far from here, the Federation is licking their wounds. This fierce machine which you have built, upon which we stand, will bring an end to the Council! To their cherished fleet! All remaining systems will bow to the Der'kal Empire! And will remember this... as the last day of the Federation!."

- General Armitage Hux

The Hosnian Cataclysm, also known as the destruction of Hosnian Prime or the destruction of the Hosnian system, was the destruction of the Hosnian system at the hands of the Der'kal Empire in 2387. The event took place during the Federation-Der'kal War and marked the annihilation of Courtsilius, Raysho, Hosnian, Cardota, and Hosnian Prime, the capital of the Der'kal Separatists. Its destruction was carried out by Starkiller Base, a superweapon capable of destroying entire star systems. With the destruction of Hosnian Prime came the destruction of the Separatist Senate and the home fleet of the Separatist Defense Fleet. The massive sub-hyperspace ripple created by the destruction of the system caused the event to be visible in real time around the galaxy, including the planets of Takodana and Vardos. When the Der'kal Empire did it, the conflict between the Der'kal Empire and the Federation escalated.

In the aftermath of the event, Lieutenant General Jack O'Neill of the Federation organized a counterattack to destroy the Der'kal Empire superweapon. The Battle of Starkiller Base ensued, resulting in the base's destruction moments before Starkiller was ready to fire on D'Qar, the location of the Federation base.

Prelude
"The weapon. It is ready. I believe the time has come to use it. We shall destroy the Federation." "Go. Oversee preparations." "Yes, Supreme Leader."

- General Hux, and Supreme Leader Vur'naa

With the goal of destroying the Federation and bringing order to the galaxy. As part of their plan, the Der'kal Empire built a fleet in the shadows of Der'kal space and constructed a superweapon called Starkiller Base, one capable of destroying entire star systems.

The construction of the Starkiller weapon marked the culmination of efforts by the Der'kal Empire to research dark energy translations and hyperspace tunneling.

During the conflict that had been going on for three years the Der'kal Empire and the Federation, Supreme Leader Vur'naa, the leader of the Der'kal Empire, considered the Federation to be an existential threat to the designs of the Der'kal Empire. Vur'naa believed that the Federation would rise up against them and defeat them. General Armitage Hux, commander of the Starkiller, argued in favor of using the weapon to destroy the Federation and the Separatists. Hux argued that without Earth, the Federation would no longer be a threat. Vur'naa agreed and gave his permission to fire the weapon.

The Hosnian Cataclysm
"It was the Separatists. The Der'kal Empire, they've done it."

- Typhuss

Under Vur'naa's order, Hux prepared the Starkiller weapon to be fired against the Hosnian system, the capital of the Separatists. When the weapon was ready, Hux addressed the legions of stormtroopers under his command who assembled to witness the destructive firepower of the weapon. Hux promised that this day would be the end of the Federation and the Separatists, the culmination of everything the troops had worked towards. Hux then commanded that the weapon be fired, and massive beams of energy were fired across the galaxy towards the Hosnian system. When they arrived, the astronomical bodies of the system were destroyed, including Hosnian Prime. With the destruction of Hosnian Prime, the capital planet of the Separatists, came the destruction of the Separatist Senate and the home fleet of the Separatist Defense Fleet. The casualties on Hosnian Prime included the Separatist Chancellor and Korr Sella. The destruction of the Hosnian system was visible from across the galaxy, and this caused terror and shock on countless worlds who had no idea of what was happening. Starfleet officers John Martin and Typhuss James Kira, along with Captain's assistant Natalie Teeger, witnessed the system's destruction from Takodana. The sight led to confusion on Takodana, but Natalie told John and Typhuss that what they were seeing was the Der'kal Empire using the Starkiller to destroy the Separatist capital.

Aftermath
"The fuel cells have ruptured. The collapse of the planet has begun." "Leave the base at once and come to me with Kylo Ren. It is time to complete his training."

- General Hux, and Supreme Leader Vur'naa

After the destruction of the Hosnian system, the war raged on the Federation mounted a reconnaissance run on Starkiller Base to learn more about the Der'kal Empire base that destroyed the Separatists. Tracing the route of the phantom energy beam, the Federation identified the Starkiller's location and Lieutenant General Jack O'Neill ordered Black Squadron to develop a way to launch a reconnaissance mission on the base.

Jessika Pava designed a minimal stealth recon ship that would be towed into the Starkiller Base system by a T-70 fighter, passively skim above the base's atmosphere while taking measurements, and then be picked up again by the T-70 fighter. While Pava planned to pilot the ship, Temmin Wexley volunteered with his wife Karé Kun piloting the T-70 fighter. The two had just been married and wished to spend as much time together as possible.

The reconnaissance mission was a success, though Wexley was barely able to make it out of the atmosphere of Starkiller Base, sustaining damage and requiring him to broadcast the data to his wife, giving up his location to the Der'kal Empire. However, she was able to recover his damaged ship by clamping it between the S-foils of her T-70 fighter, bringing them back to D'Qar. However, due to this, the Der'kal Empire was able to learn the location of the Federation base.

With the location identified, the Federation put a plan in motion to destroy the Starkiller before it could destroy D'Qar. Typhuss, Jyn, Rey, and John were sent to the weapon first to disable its shields, while Commander Poe Dameron led a fighter assault against the base's thermal oscillator, which contained the energy that it drained from stars in order to power its weapon. The Resistance forces were able to successfully destroy the weapon but at the cost of a number of Resistance lives, including Sarah Plummer and many fighter pilots.

The Hosnian Cataclysm was remembered by the Federation as the most devastating event during the war with the Der'kal Empire.