The Orange Box

You need to host a System Link game, set the map to "2Fort" rounds to "1" and start it up.

Follow the "Battlements" signs to get to the enemy base and then follow the "Intelligence" signs to get the enemy intelligence.

Follow the signs towards Battlements again to reach your own base where you can put the enemy intelligence next to your own down in the basement (again, follow the "intelligence" signs).

Do this until you have 3 captures and you will be 5 gamerscore happier. Congratulations.

Note: You do not need a second player/console and teams don't matter.

For this achievement (obtained easily), you can set up a private match, not invite anyone, and go afk for a while.

Once the time runs out, you'll get this, as the other team haven't even had a chance.

Also fairly easy to do legitimately (good defense) but this is a solution for those that want it straight away >:]

This isn’t as hard as it may seem. Join any 2Fort game you want and check to see what your teammates are doing and what classes they are playing. If you have a solid defense, then it’s time to go play some offense. If you have a friend that will help you it makes this one a lot easier. One of you go medic and the other can go any power class. With a successful uber-charge you should be able to get the intelligence, or help clear a path for a teammate to take it. If that doesn’t working you can attempt to organize a spy/demoman combo.