I haven't seen this discussed much, but I do it ALL THE TIME. Thought I would share: When I go to war, I always send a couple of workers along with the troops. I use them to build war roads: Roads over strategic hills and across rivers so that I can advance a range unit and fire in a single turn, so that I can rotate the wounded troops to the rear faster for recovery (and get them out of harms way so they don't die). Especially when a city is surrounded by rough terrain, or if there is a bottleneck, war roads are the key to victory. You can sit on the outskirts of a city just beyond its range picking off the units, while building roads. Sometimes send in a unit with heavy cover promotions to sit in the line of fire and protect a worker building a road right up to the city gate. If there are hills adjacent to the city where range units can snipe at it, I will build roads all along the hilltop during a long siege. After the war is over and the city is mine, I have the workers remove the extraneous roads so that I don't have to pay maintenance on them. BTW, this is why the roman legions that can build roads are just incredible. You could send just legions and leave the workers at home! The other thing the workers can do is repair pillaged tiles in enemy territory so that they can be pillaged a second time for faster healing -- though, sometimes I feel bad about doing that, it kind of feels exploitative. Depends on my mood. But war roads feel like real strategy and I do it all the time.