Wikipedia
A Kingsmantle ('' German language: Krönungsmantel; Dutch language: Koningsmantel; French language: manteau du couronnement) ''is a coronation mantle for the king or queen. Many princes also had a coronation mantle.
Sometimes the mantles are worn only once, but it also happened that the king used them for other ceremonies such as the opening of a parliament. Between the mantles of an emperor and king in principle there is no difference. Different countries have their own style and shape of the mantle has changed somewhat over the centuries. The oldest coats were not very long and they were not lined with fur. In the 18th century we see that cloaks become more like each other and appear everywhere in Europe. The French example was lined with fur and a cloak with a long train became standard. Only the German emperors continued their short coat from the 12th century to the end of their empire.
The non crowned but inaugurated Dutch kings wear a robe on the French model. In the Netherlands, one can not speak of a coronation mantle but use the term "royal robe." ( (Dutch phonetic: γoningsmant∂l) Belgium has never had a coronation mantle.