This mission is assigned to regain control of Regina, which fell to the sudden invasion.
After a short scene, you will be ordered to disembark. Follow the leader of alpha squad; he will take the left position on approach to Regina. Once the three groups are in position, you will be ordered to advance.
When you reach the first row of bushes, you should start to see enemies under patrol. It difficult to hit them at that range, but you can still zoom in to identify the targets. Staying to the left side of the city is the safest option, as any enemies that attack are covered by your squadmates, but don't forget the enemies that may be running around the center road.
When the squads reach the city, you will be ordered to retreat to avoid the T80s. Return in the direction you came.