Section 8

To win this achievement, you must win a bot match in the One Man Army gametype, which is a control point game with you versus up to fifteen bot players depending on settings.

To set up a One Man Army game, select Instant Action from the main menu, and modify these settings:

Mode: One man army
Difficulty: Trivial
Players: 8
Friendly fire: Makes no difference, you're the only person on your team

As for the map, you want to select any small map with only two control points, including:
Blackstone Marsh, east
Blackstone Marsh, west
Edge of Oasis
Invasion Point, cannon
Invasion Point, radar
Land's End, port
Land's End, skyhook
Nuclear Dawn
Orbital Relay, west

Now simply hit the start button to begin the game.

One Man Army is all about points over time. You gain 12 points every minute per control point you capture, and an assortment of points for killing enemies in a specific fashion. You need 1000 points to win a One Man Army match, and it takes approximately 30 minutes to play it to completion.

My recommendation is to play on the map Nuclear Dawn and capture the west base as quickly as possible. After capturing it and clearing out any straggling enemies, jetpack up to one of the beams above the second floor catwalks outside and plop down a AA gun, supply depot, and sensor array up there in that order -- supply depots allow you to resupply ammunition and change up your loadout; AA guns prevent enemies from dropping in right on top of you; sensor arrays make enemies show up on radar within a large radius.

Outfit yourself with a mortar and a sniper rifle and lay waste to enemies that approach while camping next to your supply depot. You can call for minigun and rocket turrets if you wish, just make sure not to spawn more than five deployable units or they start self destructing in order of placement to allow the new one. AA guns do not count toward the five unit limit, you are allowed two of those separately from the rest.

You will often be alerted of DCMs (dynamic combat missions, i.e. secondary objectives) like convoys and VIP escorts, but it is best to ignore these. They're free points for the enemy team but the risk of losing your base is not worth it, especially considering the neutral AA turrets in the area turn on you the second any enemy hacks the base console. In addition, the enemies vastly overprioritize these secondary objectives and you will often find yourself standing in the middle of no man's land for several minutes while they destroy a convoy vehicle or crowd around an intel cylinder forever away.

Play on any map with 2 CPs, and set the bots to Trivial, Friendly Fire On and 8 players. Capture 1 point at the beginning, and defend it for the entire game. Ignore DCMs where you have to attack, and only defend against them if they are close to your base.