SB 35 and BB 45, together with the EF76 Nebulon-B escort frigate Divad, formed the escort force of the first Death Star and were specifically tasked with protecting the communications satellite coordinating its defenses in the Yavin system.
In preparation for their assault on the battle station, Keyan Farlander, his two X-wing wingmen and an escort of two R-22 Spearheads were dispatched to destroy the comsat. While Farlander's wingmen held off Imperial fighters, Farlander ignored the threat and headed straight for the satellite, destroying it with a proton torpedo before quickly returning to base. However, both his wingmen were shot down and the pilots had to be rescued later.
The destruction of the comsat denied access to Imperial reinforcements and left it open to direct attack by unsupported starfighters. It also succeeded in slowing down the Empire's preparations for the battle, allowing the Alliance longer to analyze the Death Star plans brought to them by Leia Organa and to plan their strategy.