Mission to Onderon (Galactic Civil War)

A mission to Onderon was an ill-fated reconnaissance operation on the Inner Rim planet Onderon, undertaken sometime between 2 BBY and 2 ABY by the Alliance to Restore the Republic, better known as the "Rebel Alliance," against the Galactic Empire during the Galactic Civil War.

After the Rebel cell encharged with the mission accidentally gave away their position, the Imperial forces on the planet responded with heavy fire, prompting the Rebel command to evacuate and abandon the unit to their own devices. Scout Sasha was the sole survivor in her group, having her loyalty to the Rebellion shattered after the ordeal.

Prelude
During the Galactic Civil War, the Inner Rim world Onderon was very significant planet for the Galactic Empire in strategic terms, being the site of the most important Imperial military ordnance center in the Japrael sector, known as Jyrenne Base, which was situated near the walled city of Iziz.

The mission
Sometime between 2 BBY and 2 ABY, the Alliance to Restore the Republic decided to conduct a reconnaissance mission, sending a Rebel cell to gather information on the Galactic Empire's presence on the planet. During the operation, the designated unit accidentally gave away their position to Imperial forces when defending themselves with blaster fire against Onderon's dangerous native wildlife. The Imperials in turn responded with heavy artillery and sent a division of All Terrain Scout Transports (AT-STs) to their last known position. This mistake was critical, as it led to the Rebel command's decision to leave the recon detachment on their own, being denied any further support. Of those in the unit under fire, only Human female Sasha survived.

Aftermath
Sasha, the only survivor of her unit, went into hiding in the planet's hinterlands, remaining stranded on Onderon for some time. Her forsaking by the Rebels broke her long-standing loyalty to the Rebellion.

Sometime later, the Rebel Alliance ended up destroying Jyrenne Base in 2 ABY. This battle was one of the first direct military confrontations between Rebel and Imperial forces in the war. The destruction of the ordnance center crippled Imperial abilities to resupply its forces in the region.

Behind the scenes
The mission was first and only mentioned in Sasha's Character Folio, a freely downloadable character sheet for the roleplaying game (RPG) Star Wars: Edge of the Empire Beginner Game, published by Fantasy Flight Games as part of the Edge of the Empire RPG series. The supplement material was made available by Fantasy Flight as a free PDF eBook from their website in 2012. The last page of the Character Folio elaborates on Sasha's backstory, as well as her participation during the recon mission to Onderon.