I did some vehicle recovery training early in my military career. I don’t remember much of it other than this one exercise where the instructors drove an M113 Armored Personnel Carrier into a swamp and told us to drag it out using some ropes, pulleys, ground anchors and get this---a hand winch! An M113 weighs around 10 tons and this one was down a bank and in the mud. The winch was rated for 2 tons! We followed the instructor’s directions and set up a series of ropes running through pulleys and anchored to solid ground at the other end. The pulley was then attached to the end of another rope and so on. The theory was that each pulley/rope/ground anchor we set up doubled the weight we could pull because the ground anchors would take half the weight.