The Galactic Civilizations III campaign consisted of three levels that covered the Terran 1st Fleet's return from the Dread Lord's pocket universe up to the reclaiming of Earth from the Drengin.
A tutorial was also included that acted as a prelude to the campaign.
Arcea
At the first campaign level, you start with a fleet of capital ships and a civilian fleet comprised of a transport, a Colony Ship and a Survey Ship. you will have to go through the Drengin blockade on Arcea and take over the planet with your transports. Casualties in your capital ship fleet are to be expected. Throughout this phase, you will be prompted to make several ideological choices. Do Benevolent and/or Pragmatic choices, since those provide a Colony Ship and/or Construction Ships (you will need them early on).
Once that is done, build a shipyard near Hammer and Arcea and spam Colony Ships as described here. Use your Survey fleet to scout for any anomalies while you focus your production on building Colony Ships and Construction Ships. With those you will secure Vega. Your capital ships should clear the immediate area of hostiles while also destroying any mining starbases. Send your own Construction Ships to replace the enemy starbases, therefore increasing your resources and zone of control while reducing theirs. Since their ships are quite tough, it is adviced that you first build advanced starbase defenses on any starbase you might have.