Atlantis (NX-04) was NX-class explorer in Earth Starfleet service during the mid-22nd century during the Earth-Romulan War. The logs of the starship Discovery for August 9, 2156 recommended to Starfleet that Atlantis, along with Columbia, catch the Romulans off-guard by performing surgical ‘calvary raids’ on their outposts. (USS Baldwin: "Against the Wind")