If you Ride Roughshod over a person you treat them harshly and without consideration for their feelings. Roughshod horses have nails deliberately left protruding from the shoe in order to provide extra grip in wet or icy conditions. Being trampled on or kicked by a horse with roughshod shoes would be pretty painful. Briefly, during the 18th century, it was common practice for cavalry soldiers to make sure their horses were roughshod or had other sharp objects attached to their hooves before battle. It would mean that, during a charge, the war-horses would cut and damage enemy mounts. However, they soon found the shoes did as much damage to themselves and each other as the enemy, and so the practice ended.