Aephus was a turian colony that had a major shipyard. Cerberus targeted it for attack during the Reaper invasion in order to capture the shipyards, but former Cerberus informant and volus ambassador Din Korlack learned of the attack. He was captured by bounty hunters led by Zaeed Massani after the turian government put a bounty on him after learning of his involvement with Cerberus. After he was rescued by Commander Shepard, Korlack was reluctant to give up the information on the attack in case Cerberus learned he had betrayed them.
If Shepard managed to convince Korlack to give up the information, the turians received enough warning to prepare for the attack and repel Cerberus.