Ancestors of the modern Friesians were used in medieval times to carry knights to battle. In the 12th and 13th centuries, some eastern horses of crusaders were mated with Friesian stock. During the 16th and 17th centuries, when the Netherlands were shortly linked with Spain, there was less demand for heavy war horses as battle arms changed and Andalusian blood was added, lightening its weight and thereby rendering it more suitable (in terms of less food intake and waste output) for work as a more urban carriage horse.
Friesian Horses for Sale UK 