Alpha Group was a group within the fleet of the Rebel Alliance under the command of Admiral Gial Ackbar. The group was present at the Mako-Ta Space Docks, where it and other sub-groups were to disperse from the rest of the fleet until it was required to fight against the Galactic Empire.
As the groups were ready to launch into hyperspace, a fault occurred resulting in the ships being unable to launch which was due to Queen Trios betrayal. Shortly after the launch failure, Death Squadron under the command of Darth Vader arrived. The battle group's flagship was Admiral Ackbar's MC80A Home One Type Heavy Star Cruiser Home One.
During the battle, Luke Skywalker used his ship's light trail to signal Ackbar that his cruiser's bay doors were open. The admiral ordered the launch of all of his fighters, and for them to spread the word. Once the fleet got the codes to bring its ships online, Ackbar ordered Home One to make the hyperspace jump.