How to unlock: Complete the Call to Arms quest and talk to Rhys on the Cambridge Police Station (M5,1). It is one of the Brotherhood's random quests.
- Talk to Rhys
- Go to selected location and kill all enemies
- Go back to Rhys to collect the reward.
Cleansing the Commonwealth is one of the random quests of the Brotherhood of Steel. During it you must clear location pointed by the questgiver of all enemies - usually ghouls, supermutants or bandits. In order to take the quest, you must talk with knight Rhys on the Cambridge Police Station after you complete the Call to Arms quest from the main storyline of the Brotherhood of Steel.
After you take the quest, you will be pointed to a random location that you haven't cleared of enemies before. Usually you don't even have to kill them all, eliminating the strongest ones marked with a green point is enough. Once the objective is completed, go back to Cambridge Police Station and talk to knight Rhys. You will receive some bottlecaps from him, gain some experience and you will be able to start another similar mission.
Quest rewards: experience points, bottlecaps, new side quest.