Ab Dalis was a world of swampy wastelands located within the Ab Dalis system along the Corellian Run in the Outer Rim Territories. This planet was controlled by many corporations run by the wealthy elite, and its corrupt government was ineffective and catered to their needs. Workers resided in slums while the elite lived in towers, and city-sized factories were operated by them. Following the Great Hyperspace Disaster, in which the freighter called Legacy Run disintegrated in hyperspace, Ab Dalis was struck by the first Emergence. A fragment of the destroyed starship, which everyone assumed had been dealt with in the Hetzal system, impacted the planet, killing around twenty million individuals. The impact caused a massive crater and cracked the planet's crust, leading to tectonic instability. Consequently, the planet was abandoned due to the hazardous conditions.
Centuries later, Ab Dalis became the location of Rendezvous Point Lambda-Four, a Rebel Alliance base situated near the impact crater, which included a resupply depot and mechanical facilities. After the Alliance Fleet scattered after the Battle of Hoth, the Eleventh Division, including prominent rebel figures like Mon Mothma and Admiral Gial Ackbar, assembled at this rendezvous point. The Galactic Empire eventually discovered the rebels, and Commander Ellian Zahra dispatched Admiral Kalaxo of the Star Destroyer Ultima II on patrols to locate the scattered rebel divisions. Before they regrouped, he decided to destroy them himself. Despite the Empire's success in eliminating the ground defense base, the Alliance's Starlight Squadron, along with Jedi Padawan Luke Skywalker, triggered a volcano beneath the Ultima II, which destroyed the Imperial capital ship, resulted in Kalaxo's death, and rescued Mothma and the remaining rebels.