Distant Thunder is an annoying mission, not least because of a bug in the AI behavior that can render it unwinnable. Here's what you need to do.
Guide to Get Mission 5
The Hidden Requirement
The mission script requires letting an enemy MCV (which you'll see in their starting base) to escape and build a base on the island (which you will then have to destroy):
This normally wouldn't be a problem, except that the MCV's AI is extra stupid and can randomly get stuck in its' initial position instead of going onto the transport, making the entire mission unwinnable.
If you let the MCV escape and spend time establishing a base on the island, the mission will also get unwinnable - the island has massive ore fields and you simply won't have the resources to crack it.
The MCV won't start moving until you do one of three things:
- Assault the AI base.
- Build a Sub Pen.
- Land paratroopers on the island.
Don't do any of these things until you're ready to take out both the main AI base and the island expansion (more on that below) and save your game first.
The MCV will not always enter the bugged state if you do the same thing after reloading, so you can just reload and retry.
Scout the island using spy planes
The area that interests you is the large plateau to the northeast:
Prepare a BIG flight of Yaks
You need to destroy the Construction Yard on the island base shortly after it deploys, before it builds anti-air defences (see: unwinnable scenario #2, above).
Making things a bit worse, this MUST be done with a single attack or the Yard will repair to full (and continue building the expansion) before your planes rearm.
On Normal difficulty, you will need a flight of 10 Yaks yo do this.
Get ready for the rush hour
Destroying the island Construction Yard will trigger another fun event: all of the AI's ships will rush you. Since you don't have a Sub Pen yet and your Heavy Tanks can't compete with the range of enemy Destroyers and Gunboats, you will need to ready a pile of V2 launchers.
Helpfully, massed V2s are also a good solution against the first AI base's gun emplacements.
There will still be some cleanup to do
The AI will still have a few units left on the island (and possibly a handful of naval units that haven't participated in the rush). You should be able to take care of them with a combination of your Paratroopers and Yaks.
The transport ship that delivered the MCV to the island will continue to aimlessly float around, so don't forget to destroy it as well.
Getting Allied tech can help
If you capture the AI Construction Yard, you can build a Naval Yard and from there some Gunboats of your own (which will help with the straggler Gunboats and land units on the island, if you can draw them to one of the shores eg by using Paratroopers).
As we all know, all you need to capture a CY is to get some Engineers and run them into the building when it's damaged - but on this map, the area around the Yard is packed with explosive barrels. If you just go and cap it, the barrels will explode and wipe the damaged Yard off the map - destroy them first, then capture the yard and enjoy the repossessed products of capitalist science!