Story related, cannot be missed.
This mission requires you to steal a Goliath, the huge tank like vehicles, during the story.
When you enter the Shipyard, you'll need to get your weapons from the inside guy. Once you reach the gate they are behind, youll need to craft a hacking device (battery + chemicals) which you must scavenge.
The chemicals are in the same room, in a blue shipping container.
The batteries can be found further along, beyond a chain link fence, in a dumpster (there's cache graffiti as well).
Get your weapons and make your way to rendezvous with Jack. You must then defend the Goliath while Heather gets it started. This consists of a few waves of enemies, and about 4 heavies. Watch the sides for snipers on the pipes.
After defending the Goliath, you'll need to escort it out. A few Wolverines will show up, hack them to make it easy on you, and watch for RPGs, Jack usually let's you know they have spawned.
When you reach the end of the street, a cutscene will play and you'll unlock the achievement.