Laurel Wreath
Win 50 rounds playing online. (Multiplayer)

First make sure when you create a player profile, the setting Internet Player Profile is set to Yes. Then Login go to Multiplayer then Internet and then Create a Game. You will want your settings set to:

Match Type: Capture the Flag
Map: Ruins
Min Player: 1
Reward Limit: 5
Time Limit: 5:00

Now you can start the game. Since you are by yourself it will be very easy and fast to capture the enemy flag. You can capture 5 times and win the round in about 4 minutes. It will take approximately 3 hours and 20 minutes not including menu and loading times to get this achievement. Since its a custom match it will be less likely someone will join than a server match. Also you wont have to switch maps every game, which could change to a larger map that will take more time. From the maps I have played Ruins is the shortest distanced and most straightforward map. I hope this guide helps you get this achievement and saves you some time.