Two crawler tractors, a length of surplus naval anchor chain, and a few hundred metres of open ground between them. Chaining is among the bluntest instruments in land management, and also one of the most mechanically elegant. The method is simple in layout. Two large crawler tractors drive parallel courses, dragging a heavy chain between them in a U or J shaped loop. Anything rigid and upright in the path is pulled over and, ideally, uprooted. The mechanics behind it: - The chain meets the trunk above ground level, so tractive force acts through a lever arm and generates a large bending moment at the base - When that moment exceeds the anchorage capacity of the root plate, the tree rotates out of the soil rather than snapping - Chain mass keeps the loop low and in contact; lighter chain rides up and over vegetation - Swivels allow the links to roll, shedding debris and disturbing the seedbed - Heavy steel balls or weighted links are often added to stop the chain riding up and to brea...