In 2262, Tannier along with Ranger Rastenn were chosen by Sech Turval to accompany Sech Durhan and himself to visit Entil'Zha Delenn on Babylon 5. After passing the rite of Mora'dum, Entil'Zha Delenn requested that Tannier be assigned as a house guard when the Interstellar Alliance moved its headquarters to Minbar later that year.
In 2265, Tannier was made Captain of the new prototype ship Valen. The Valen's first mission was escort a delegation of IA diplomats from Minbar to an archaeological dig site on Beta Durani VII. Tannier requested that the Liandra - a ship recently given to Shok-na David Martell - to serve as escort for the mission. Upon arrival, both ships were attacked by an unknown alien race almost as soon as they exited hyperspace. With both ships crippled, Tannier ordered the diplomats into the life pods while he and his crew stayed behind to buy time for the Liandra to escape with the ambassadors. Tannier rammed the Valen into the alien vessel, destroying both ships and all aboard.