The Marshal of Atrios was the commander of his people's war against Zeos.
The Marshal was secretly under the Shadow's influence, having been hypnotised. He contacted the Shadow through an object that resembled a skull. At his master's behest, the Marshal launched a final strike against Zeos, unaware that Mentalis had started its self-destruct program, which would also destroy Atrios.
The Fourth Doctor placed him and his ship in a time loop using the Key to Time. However, this began to gradually weaken. The Doctor redirected the Marshal's attack against the Third planet, destroying it and apparently killing the Shadow.
Drax planned to start a business with the Marshal repairing the war damage to Atrios. (TV: The Armageddon Factor)
