Highlight from 'The Greatest Knight' by Thomas Asbridge

For general riding and travel, William used a light ‘palfrey’, while a stout and stocky ‘sumpter’ carried baggage, weapons and armour. However, Marshal’s most valuable mount was his destrier or warhorse – the animal ridden in combat. These cost anywhere from £40 to £100, sometimes even more. Working from the rates current in the 1160s, for the average price of one destrier William could have purchased either 40 palfreys, 200 packhorses, 500 oxen or a staggering 4,500 sheep.