You will drop down onto a nearby harbour with an arguably awful loadout as usual.
Fortunely, a supply depo will drop nearby. Change your loadout as needed.
Eventually, you'll come across an incredibly large building with a road leading through. Do NOT run all the way inside. You will be utterly rushed by several enemy heavy mechas. Keep your distance and either blow them away with a rocketlauncher or a sniper.
There will also be a few hostile commando's lurking about. Proceed with caution, or with a LMG.
Most enemies WILL punch through your shields. Having a repair tool is recommended.
After a dozen of difficult enemies, you'll come across this console. Disable it to turn off the enemy generators.
Once down, run west up towards a large field, crawling with baddies.
Amongst the baddies will also be heavy mechas. Imbalaned or not, they WILL very effectively gun you down for large amounts of shield-penetrating damage across laughable distances. Keep clear and wait for your teammates or die.
I recommend flying up on the pipelines with a sniper rifle and picking away at anything you see before it's all clear.
Once enough enemies are killed, get down and up to the console and hack it.
You'll come to a final, large building with the features of a tower.
Run into the building and get thrown into a cutscene.
A boss will emerge with a downright laughable amount of HP. Once he surfaces, I recommend running away as far as humanly possible. His team of commandos and other elite units cannot be killed permanently but respawn repeatedly after death.
He WILL chase you whenever he can, and that includes sniping you with machineguns. Stay FAR away behind cover.
As attractive it is to kill his fellow soldiers, don't bother. They will respawn within seconds.
Shooting his shoulders/head will very often result in a miss..
Instead, shoot his mid-section.
He may seem invulnerable but stay diligent and keep throwing lead in his direction.
About half-way through his HP, enemy "engineers" will show up, running after him constantly and applying healing. Take them out first.
After many, many, MANY sniper rounds, he will eventually die, ending the mission.
You will be thrown into another cutscene where he comedically enough dies to a knife and a pistol, ending the single-player campaign even if his teammates are still alive. Good work soldier.