In Tavis's recent playtests, questions arose about the movement speed of artillery and war machines during campaign-level activity. The following rules address this.
Movement of War Machines
War machines, which include all types of artillery, battering rams, galleries, hoists, screws, and siege towers, can be moved either assembled or disassembled. Assembled war machines move at a rate of 30’ per turn (6 miles per day and 24 miles per week), while disassembled war machines move at a rate of 60’ per turn (12 miles per day and 48 miles per week).
Assembling and disassembling a war machine is a construction project with a construction cost equal to 1/100 the cost of constructing the war machine from scratch (minimum one day). Disassembled war machines cannot be used until they are assembled, so an army that has to suddenly pitch battle, or is ambushed on the march, will not have access to any disassembled artillery and other devices.
EXAMPLE: A Roman legion with 1,040 men has four heavy catapults (600gp each). It has to march 120 miles to lay siege to a Gallic fort. If the legion marches with its heavy catapults assembled, it will travel at 24 miles per week, and take 5 weeks.
Disassembling the catapults is a set of four 6gp construction projects, each of which can have up to 50 men assigned to it. Each man has a typical construction rate of 1 2/3sp per day, so each project has a construction rate of 8.3gp/day – thus it takes just one day to disassemble the catapults. The legion can then march to the Gallic fort at 48 miles per week, and get there in 2 ½ weeks. It then takes one day to assemble the catapults on arrival.