The Human Campaign: - Imperial Knights and Cybrids
Mars Resistance, Imperial Knights and Cybrids, Against the Cybrids

Mission #8: Imperial Retaliation
Defending Ophir Station sounds pretty easy, but the Imperial knights will hit it somewhat randomly in four or so waves from multiple directions. When faced with multiple enemies, assign two of your squadmates on one enemy and then go one-on-one with the others if you can. The gorgons can be extremely tough, so gang up on them whenever possible. You can also use the map to place your squadmates at strategic locations around the base.

Mission #9: Hunting the Icehawk
This one is tough - bring some ECM gear. Move through the canyon, engaging and destroying whatever land-based opposition you may encounter (the talons will initially run away once you first encounter them, leading to some more basilisks and then two nasty disrupter tanks). Ignore the ships flying overhead; they are only important for secondary objectives (and are coincidentally extremely hard to shoot down properly).

 
  A very busy area full of Imperials.
   

The canyon will open up to a wide-open area filled with six Imperial dropships and various harmless support vehicles and cargo containers. Off on the right-hand side of the area is the base at Nav Charlie, which is protected not only by a missile turret, but a tough gorgon and an even tougher apocalypse nearby. Other Imperial hercs may be nearby, near the dropships perhaps. Try to take down some of the dropships if you can and get the other squadmates to help, but be sure to do this before taking on the base. Also watch out for incoming Imperial artillery.

The important thing is taking out the base - first the turret, then the gorgon. The apocalypse will soon rumble up - concentrate everyone on it and keep doing it until it's destroyed. It won't be easy. Fortunately, the apocalypse is also a bit slow, so you can stay behind it somewhat easily.

Once you have control over the base, and no Imperials are within radar range, the mission is won.

Next: Missions #10 and #11next