What is a coat of plates?
Glad you asked! It is jacket (coat) covered on the inside with plates. This provides protection against angry people, pointy sticks and other nasty things. This is my coat of plates:
As you can see, the plates are on the inside of a fabric or leather jacket there are plates rivited to it. These plates provide the actual protection, the fabric is just a way to keep them together
When was it used?
The coat of plates started to appear in the late 12th century when it was state of the art and only for the elite. It became mainstream in the 13th century and in the 14th century it was on its way out. In 1361, during the battle of Wisby, the poor defenders used coat of plates, and they were really outdated.
How was it used?
The coat of plates was worn over a chainmail hauberk (a long-sleved shirt of chainmail). It's advantage over chainmail was that is was resistant to percusive weapons like maces and warhammers. The plates are very good at destributing the blows and thus they solve one of the disadvantages of chainmail.
What are its strangths?
Due to the simple shape of the plates, most of the work on this armour is in riveting the plates. This means it was very cheap in the Middle Ages, when unskilled labour was very cheap.
Because the plates overlap, when they are hit they find support on the plates they overlap and through that overlap they spread the blow over a large area.
While the plates overlap, they are not connected with rivets or anything else. This means they can slide over each other. This is a good thing because it allows the wearer to sit down and bow while wearing it.
What are its weaknesses?
The coat of plates is not suited of pieces which require a lot of movement like the elbows and the shoulders.
It is very dependant on the fabric, so if the fabric is cut appart, it weakens the coat of plates significantly.
Why and with what was it replaced?
It was replaced with the brigandine and plate armour. I will write more articles about them. Plate armour was better resistant to blows and had less weakpoints. The brigandine provided more mobility.
Thanks for reading
Sources:
Amazing piece of research by Prof. Dr. Matthias Untermann
Thordeman, Bengt (2001) [1939]. Armour from the Battle of Wisby, 1361