A rail mercenary is a civilian mercenary hired to serve on the Factory Railroad and protect the trains from attack, making them members of the Factory Army. They are paid on a per week basis, including meals, and are equipped with rent-a-guns. There are no real qualifications to become a rail mercenary, except for a willingness to do so. Applicants who are recruited at a Factory train's departure site sign the contract, are equipped with rent-a-guns, and placed on the train they will be serving on, with two mercenaries per train car.