Anti-air is the key to surviving and that is the key to winning this level. Do not use rocket troopers for this purpose, use Gatling cannons. Initially, build 6-8 Gatling Cannons halfway between your base and the river. Do it quickly because you need to have them up and running before the initial assault. The anti-missile defenses on the air force general's planes renders 90% of the rockets fired useless; however, Gatling cannons will rip his planes to shreds. A few Gatling cannons will be destroyed, but as long as you keep repairing and replacing them you will be safe. Extend the Gatling cannon line to the southeast as your base expands.
At the start your initial priority should be to build a second dozer, a barracks, supply depot, 6-8 Gatling cannons between your base and the river, and the power structures to run everything (with a backup just in case). Leave space around your barracks to minimize collateral damage from the B2 bomber runs. Be sure to train a red guard unit and research capture building to get the oil derricks and keep the cash rolling in. You can capture the second Oil Derrick to the north of the base for an extra $1000. However, it will likely be destroyed early as it is difficult to defend it in the early part of this level.
After you are well defended start building your base. The order should not matter much, but it is advisable to focus on getting hackers and an internet center to keep up your cash flow. If your supply pile empties, you can get more supplies to the east.
If you can get a nuke quickly, the first target should be the enemy supply center. That is where they keep their planes and Apaches patrolling when they are not actively attacking you. Also if you hit this area with a nuke before their initial supply pile runs out, you will take out many of their supply choppers. However, after one strike in this area you are better off targeting his airfields and the rest of his base.
After their initial supply pile is empty, they will start emptying the one in the center of the town in the middle of the map. On hard difficulty they will also have a large garrison force here, the size of which will actually prevent your nuke bomber power from making it to the enemy base.
Once again, your air power has little use on this level; enemy raptors will easily shoot your planes down. After your base is up and running send out forces of overlord tanks to dominate the map. You need to have a few speaker towers on your overlords to heal, but you should favor Gattling cannons to defend you overlords against the inevitable attack from the air.
If you can survive the initial air assault at the beginning of the level, the rest of this level will be easy in comparison.
First off, build a barracks, Red Guard, and Capture Building. Send one RG to capture the oil derrick to the south, and the other RG to capture the far NW oil derrick.
Build reactor and supply centers as usual, then build two Gatling Cannons, one near the NW oil derrick, one east of the beach houses. Build your War Factory as soon as possible, and start sending out Gatling Tanks. Spread the tanks around the north part of your base.
The first assault will be a bunch of para-dropping rangers. If you've built enough Gatling Tanks, the rangers won't last long. More assault waves will follow; the toughest to deal with are the King Raptors. You're going to lose some Gatling Tanks to these, so keep building them to replace your losses. Make sure your War Factory is covered well by anti-air, or the Raptors will destroy it and you'll find it hard to recover.
Get your Propaganda Center built, then build Speaker Towers in the northern area of your base. This will heal your Gatling Tanks, and allow your dozers to repair your Gatling Cannons without being destroyed.
Next, build two Nuke Silos. Priority targets are the enemy supply center, supply drops and airfields. Purchase the Subliminal Messaging and Chain Gun upgrades. Build an Internet Center and fill it with Hackers to increase your income, and buy Satellite Hacks 1 and 2.
For your Generals' powers, buy level 3 Artillery, Carpet Bomb, and EMP. The Carpet Bomb is useful for taking out the Patriots at the entrances to the enemy's base.
Grainger is not very adaptable in his tactics, so he'll continue to send air assaults at you until he runs out of money.
At this point, send a dozer protected by 2-3 Gatling Tanks across the east bridge and build a second supply center. Build a second War Factory here and start building Overlords for your assault on his base. It is recommended to upgrade half your Overlords with speaker towers, and the other half with Gatling Cannons. You can also try using Nuke Cannons, but they may not work well since they become priority targets for his Raptors, and it's hard getting them up the mountain to his base. Remember to get the Isotope Stability upgrade to minimize collateral damage from destroyed Overlords. You will need to pass through a village with a few garrisoned structures, so you might want a Dragon Tank or two.
At this point you just need to take out the patriots guarding the base entrance. Destroy them one-by-one with your Overlords, taking time to heal between each. You will likely be attacked by Comanches and/or King Raptors as you ascend the mountain, so keep your Overlords together so they all stay covered by Gatlings and Speaker Towers.
Once you get in the base, destroy all his airfields first - otherwise his Raptors will continue to hammer you. Black Lotus is useful for capturing buildings once you've cleared the Patriots. Proceed to claim victory.