A chapeau is a flat-topped hat once worn by senior clerics.
In European ecclesiastical heraldry, it is used as a mark of ecclesiastical dignity, especially that of cardinals, where it is called the red chapeau. It is worn over the shield by way of crest, as mitres and coronets are. A galero chapeau is flat, very narrow atop, but with a broad brim, adorned with long silken strings interlaced; suspended from within with rows of tassels, called by the Italians fiocchi, increasing in number as they come lower. The hat was given to them by Innocent IV in 1250, but was not used in arms till the year 1300. Until that time, the cardinals were represented with mitres. Archbishops and patriarchs bore a green hat, with four rows of tassels; bishops wore the same color, but with three; abbots and apostolical prothonotaries with two.
The chapeau is also sometimes used as a mark of secular dignity, such as a cap or coronet armed with ermine, worn by dukes, etc. In this case, the chapeau may be used instead of a helmet to support the individual's crest, since the rules of heraldry do not allow a crest to be placed directly on the armorial shield.[1]
In the Anglophone heraldries, a "chapeau" or cap of maintenance is a specific kind of hat.[2] It occurs as a charge, but also more importantly as an exterior ornament, signifying rank.
The use of the chapeau in English heraldry is not as clear cut and regulated as in Scottish heraldry.
The chapeau represents Scottish barons in historic heraldry instead of a coronet.
Scottish barons were entitled to a red cap of maintenance (chapeau) turned up ermine if petitioning for a grant or matriculation of a coat of arms between the 1930s and 2004. This chapeau is identical to the red cap worn by an English baron, within the coronet. Like a coronet, it is sometimes depicted in armorial paintings between the shield and the helmet. Additionally, if the baron is the head of a family, he may include a chiefly coronet which is similar to a ducal coronet, but with four strawberry leaves. Because the chapeau was a relatively recent innovation, a number of ancient arms of Scottish feudal barons do not display the chapeau. Now, Scottish barons are principally recognised by the baron's helm, which in Scotland is a steel helmet with grille of three bars, garnished in gold. Occasionally, the great tilting-helm garnished with gold is shown, or a helmet befitting a higher rank, if held.