Mutineer Highlanders

[Plynkes]

The highlander hat is a feather bonnet, made from ostrich feathers, different to a guardsman's bearskin. But that doesn't actually answer your question, to which I don't have a definite answer.

I think it is that the 1st Foot Guards took the idea of wearing such a fur hat as a sort of trophy or memento from the French Guards, after defeating them at Waterloo. Grenadiers of all countries had been wearing furry hats for ages, and after the 1st Foot Guards started styling themselves as the Grenadier Guards I suppose it made some sort of sense. The other Guards just followed the fashion, I guess.

[Argonor]

Just like the Scots Greys picked up the bearskins of some fleeing french grenadiers and started wearing them  .

As to bearskins - they are actually a hugely exagerated fur rim on a grenadier's cap. Grenadiers abolished the use of broad-brimmed hats in favour of a long soft cap (often red, and trimmed with coloured 'rope'), not unlike the ones worn by scandiavian folk dancers, actually, often with a fur rim, as the hats got in the way when throwing grenades. Some put metal plaques on the front with regimental badges and such - these were in some countries elongated, thus creating the mitre caps - others over time had the fur brim elongated, at the same time shrinking the cap, until only a coloured patch remained on top of a bearskin.

[Totleben]

Here's something I've been puzzled by for a while: why bearskin on British troops? Not a lot of bears in the British islands, are there? Or is that because they were all shot so that their arses could be tacked into silly hats?

Grendiers of catholic states  normally wore fur hats, protestants the mitre cap. The fur for the british bearskins came from canada, they use fake fur since a few years.

[Hammers]

I bow to both your knowledge. Now that you say it I think I remember that bit about bearskin being a Napoleonic trophy piece of fashion.

[Argonor]

Grendiers of catholic states  normally wore fur hats, protestants the mitre cap. The fur for the british bearskins came from canada, they use fake fur since a few years.

That's interesting - also the British grenadiers and fusiliers started wearing bearskins rather late, using a mitre-like cap up through the most of the 18th century. At the time of the AWI there seems to have been a bit of mixed styles.

Russians, being neither, adopted the Prussian mitre caps under Peter the Great (I think), and some regiments kept wearing them all the way up to WWI - the SAME - being handed out to the soldiers, often with bullet holes in them 

I have to look into, when the Danish Royal Guard started using bearskins.... 

[Totleben]

That's interesting - also the British grenadiers and fusiliers started wearing bearskins rather late, using a mitre-like cap up through the most of the 18th century. At the time of the AWI there seems to have been a bit of mixed styles.

Russians, being neither, adopted the Prussian mitre caps under Peter the Great (I think), and some regiments kept wearing them all the way up to WWI - the SAME - being handed out to the soldiers,m often with bullet holes in them 

I have to look into, when the Danish Royal Guard started using bearskins.... 

Take it as a rule of thumb for the 18th century, esp. for german/central europe states. Later the dress code might have  been influenced by political affiliations and/or military fashions.