The glengarry bonnet is a traditional Scots cap made of thick-milled woollen material, decorated with a toorie on top, frequently a rosette cockade on the left side, and ribbons hanging behind. It is normally worn as part of Scottish military or civilian Highland dress, either formal or informal, as an alternative to the Balmoral bonnet or tam o' shanter.

Traditionally, the Glengarry bonnet is said to have first appeared as the head dress of the Glengarry Fencibles when they were formed in 1794 by Alexander Ranaldson MacDonell of Glengarry, of Clan MacDonell of Glengarry. MacDonell, therefore, is sometimes said to have invented the glengarry - but it is not clear whether early pictures of civilians or fencible infantry show a true glengarry, capable of being folded flat, or the standard military bonnet of the period merely 'cocked' into a more 'fore-and-aft' shape. The first use of the classic, military glengarry may not have been until 1841, when it is said to have been introduced for the pipers of the 79th Foot by the commanding officer, Lieutenant Colonel Lauderdale Maule.

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