Several mission types cause a small battle.
Its specialty is "corruption:" it can conquer planets traditionally, but also gain bonuses from enemy-controlled worlds by having its infiltrators conduct any of several kinds of missions such as bribery, sabotage or piracy. The Consortium has a full-fledged campaign that's set in the background of the film trilogy. The Zann Consortium is a newly invented faction, neither good or evil, but willing to go to any lengths for a profit.
Pirates had previously been present in the game, but as a type of moderately-armed "speed bump" to progression in the war between Empire and Rebellion. Star Wars: Empire at War: Forces of Corruption adds the organized crime syndicate the Zann Consortium as a third faction. A screenshot of the Galactic map during gameplay (playing as the Zann Consortium)