It's time for the Empire to strike back as take part in the Battle of Hoth.
Personal Hints:
-It's a good idea to subdivide your forces into groups to better counter what the rebels send at you. (Pummels in one group, Anti Air in another and so on)
-Blizzard Force will be your main means of taking out buildings and enemy mechs when you get them, so make sure they're protected. That said, only Veers is required to survive so don't worry if one of the others goes down.
-When attacking green's base, make sure to take out the grey troopers near the transports. If one's still alive when the last Airbase is destroyed, you'll fail the mission.
-Keep your anti air alive. You'll need them to deal with enemy Airspeeders.
-Yellow and Cyan have mostly the same forces (Troopers, Mounted Troopers, Strike Mechs, Mech Destroyers and the occasional Artillery and Airspeeder.) Destroy their production buildings to stop the flow of enemies, but they'll resign when you destroy the Main Power Generator and Ion Cannon respectively.
-Don't move Vader's force until you deal with red's turrets near them.
-Red's base is tough. Not only do they have all the units you've had to face so far (now including Assault Mechs and Grenade Troopers) but they have several upgrades. Their fortresses even have enough range to attack your walkers, so use your pummels to draw their fire while the AT-ATs provide extra damage.
-Red has a small base southeast of their main one. I found it's best to attack it after you clear out Echo Base proper.