Ditching logs, used to great extent by WW II German panzers, especially in Russia. If the tank is bellied up or bogged down in mud or soft turf, the log is placed across the tracks and chained or roped to the tracks. By driving forward, the log is pulled under the tank and in most cases, pulled off the obstruction or out of the mud. Problem in mud is that you can only go the length of track on the ground....then take it off, carry it to the front and tie it on again. Does NOT work well in rice paddies. [:'(]