Okay a guy I know is claiming that Medieval Warhorses were only 14 hands high. I argue that throughout the ages (AD 1- present day) there have always been horses 15-16 hands high.

So does anyone have any sources to help me?

This topic may be of help: http://www.myArmoury.com/talk/viewtopic.php?t=15169

Read Andrew Ayton's "Knights and Warhorses".

Ann Hyland's book (despite some faults and biases) are good sources -The Horse in the Ancient World; Equus; The Horse in the Middle Ages; The Medieval Warhorse ; and The Warhorse 1250-1600.

The short answer is that you are both right. Earlier medieval (11th century) warhorses could be, and often were, 14 hands, and the early Mongol armies used strings of even smaller horses, but particularly from the 14th century there were active programs to breed larger horses that would consistently reach 15+ hands and be able to carry more weight of rider and armour. These larger horses had also existed in the Roman world, but required consistent efforts to keep the breeds large by careful stud management. After the Roman stud system broke down, horses reverted over time to the smaller sizes, so by Carolingian times they were back to mostly 13-14 hands.

I am sorry for the elementry question, Though as I skimmed over the other articles I find myself asking; What do the number of hands mean?

A hand is a unit of measurement that is used to measure the height of a horse from the ground to the withers (front shoulder). It was originally the length of a mans hand but today it is a standardized to be 4ins. I found this information using wkipedia.

If it's standardized, is there a reason to use the archaic system? Why not say the horse is 60" high?

M.

Or, conveniently, a Hand is 10 cm... so you can use it interchangably, without having to do any counting...
When we are talking of replacing archaic units ;)

Sirs-The basis of all warhorse size is your stud system and Logistics. A 15-16 hand horse Cannot find enough food foraging for itself. Mongol and similar horses can. Heavy warhorses are grain fed, and that is why when the Roman Army logistics system broke down the stud system failed. "To march, first you must feed" as the duke of Wellington used to say.