Atoko was an Admiral in the Galactic Alliance Fleet and, as of 40 ABY, the commander of the Galactic Alliance Fifth Fleet.
Atoko rose through the Galactic Alliance ranks to become an Admiral, taking over command of the Fifth Fleet by 40 ABY. He participated in the Battle of Kuat before Chief of State Colonel Jacen Solo withdrew the Fifth and ordered them to Kashyyyk, where the Fifth protected Caedus's flagship, the Anakin Solo, while Caedus bombarded Kashyyyk, where the Wookiees were sheltering the Jedi, newly declared traitors to the Galactic Alliance. The Fifth was badly savaged when Confederation forces arrived to relieve Kashyyyk, and Atoko prepared to scuttle his ships rather than let them fall into the hands of Wookiee boarding parties. Caedus ordered Atoko to continue the seemingly suicidal fight, and the last elements of the Fifth were only saved when Caedus, using his battle meditation abilities in conjunction with those of Dark Jedi Alema Rar, was able to run the Confederation gauntlet. After the Mandalorian attack on the Moff Council during the Second Battle of Roche, Atoko was assigned to attack the Mandalorian homeworld with the remnants of the Fifth Fleet and neutralize the threat they represented to Caedus. During the battle, Atoko release tons of a nanovirus targeted against Mandalore Boba Fett, rendering him and anyone who carried the Fett gene unable to set foot on Mandalore, possibly killing the surviving clones from the Clone Wars and any children or grandchildren they may have had.