Command and Conquer 3 Walkthrough GDI Mission 14, Berne

This can be a very tough mission, because you are almost always facing assault. Your best bet is to begin the fight on the defensive. Build a crane, then two additional refineries (sell them to get harvesters) followed by a power plant and tech center. Build two to three sonic emitters at the northeastern fringe of your base so they can cover all angles. A war factory being built while your construction yard is working on the tech center will help much early as well, in that you can start producing APCs.

The air base is probably the most annoying of the two secondary objectives. Build about ten APCs (don't leave your base's air defenses weak!) two mammoth tanks and eight zone troopers. Take with them a surveyor to keep behind your force to expand once fighting is over. Head to the east, avoiding much of the action in the center, and snake your way north. Try to goad the aircraft in the base into attacking so your APCs can finish them quickly. Afterward, focus fire on defensive structures to eliminate them as swifly as possible. Deploy the surveyor and two refineries. Keep both refineries to speed income. There is a tiberium spike to the north of this area that can be captured, but could be difficult to hold. Still, its bonus 750 tiberium and a few seconds worth of income is better than none.

Continue to defend and set out to capture as many tripods as you can. Escort the engineers on this task as they are very squishy and will get hit by the incessant gun walker attacks. Keep replacing your sonic emitters and when your defensive tab is clear you can build an ion cannon.

Repair the gun walkers and work on building an army similar to your first (who should still be guarding). Take them up the western side of the map and treat the fight very similar to the first, except perhaps with an additional tripod or two helping. This base should go down faster than the first. If you have trouble with it, your ion cannon is always an option (but one that I did not need).

With the second base down a lot of the heat will be off of your forces. Build up your army and attack the enemy base from the eastern side of the map. Using the ion cannon to clear the defenses around the objective is a great touch, and damaging the drone platform in this fashion makes it much easier to finish off.