This mission marks your first encounter with the Zerg race in the Starcraft 2 single player campaign and follows directly behind the mission “The Outlaws”. After conquering the Dominion base and securing the alien artifact, you will have to hold out for extraction while defending against an onrushing Zerg Swarm. There are two critical points which you will need to defend to prevent the Zerg from breaking through. Fortunately, they are narrow choke points which you can further fortify with bunkers to make the task easier.
As soon as the mission starts, deploy an SCV to build additional bunkers at the choke points while sending all nearby troops into the existing bunkers to garrison them. Remember to garrison your bunkers with a new batch of marines once construction completes. You can leave your SCV there and it will automatically repair the bunker the moment it takes damage. Do not delay as the first wave of Zerg will be coming right around that time.
After the first Zerg Wave has been taken out, an SCV will be automatically deployed to the other choke point. Instruct it to build second bunker and prepare to rescue some rebels trapped on the outskirts of your base. The rebel fighters are a bonus objective for the mission and will call for distress three times with all three at different locations. The first group is situated at the northeast not far away from the Backwater Station, the second group is situated north of your left bridge and the final group is located on a plateau northwest of your base. Rescuing them also provides you with additional resource pallets that can be scooped up by your units at the respective rescue locations. You want to bring on a slightly additional force of about 10 marines supported by medics for the third group as they are surrounded by a small group of Zerg forces.
The key to victory in this mission is defending your two choke points well. Force the invading Zerg units into the choke point where they can be focus fired upon and immediately repair or rebuild any bunkers that have been destroyed in a raid. Towards the second half of the mission, the Zerg will send in Mutalisks to assault your base. These are flying units which won’t come in by the choke points. Add a few more missile turrets to keep them in check and station one or two SCVs nearby to repair any damage sustained during raids. The attacks will get increasingly more intense but as long as you stick to your battle plan, you will be able to finish this mission with ease. As long as you have at least one structure standing when the countdown timer hits zero, your mission is a success.