Colonel Caldwell arrived at Atlantis during the Wraith siege, but he came to help. Commanding the Earth's newest battle cruiser Daedalus, he was able to help Atlantis beat back the Wraith Fleet. Caldwell takes command if both Weir and Sheppard are out of commission. During his time at Atlantis he was found to have a Goa'uld controlling him. Thanks to the Asgard the Goa'uld was removed and Caldwell now finds himself trying to regain the trust he once had.