The term came to denote a hat,usually associated with Scottish Hat military regiments, derived from the old bonnet, along with the Glengarry and the Balmoral bonnets. The Balmoral was sometimes simply described as synonymous with the tam o’ shanter. … Women have also adopted a form of this hat, known as a “tammy” or “tam”.
The tam o’ shanter is a flat bonnet, originally made of wool hand-knitted in one piece, stretched on a wooden disc to give the distinctive flat shape, and subsequently felted. The earliest forms of these caps, known as a blue bonnet from their typical colour, were made by bonnet-makers in Scotland. By the year 1599 five bonnet-makers’ guilds had formed in cities around the country: Edinburgh, Glengarry Bagpipe Hat,Aberdeen, Perth, Stirling and Glasgow. At the end of the sixteenth century, it was said that the Scottish tam hat were the normal fashion of men and servants, and they remained so throughout the seventeenth century.
Similar in outline to the various types of flat bonnet common in northwestern Europe during the 16th century, the later tam o’ shanter is distinguished by the woollen ball or toorie decorating the centre of the crown; the name itself did not enter common usage until the early 19th century, subsequent to the popularity of Burns’ poem. The term came to denote a hat, usually associated with Scottish tam hat military regiments, derived from the old bonnet, along with the Glengarry and the Balmoral bonnets. The Balmoral was sometimes simply described as synonymous with the tam o’ shanter.
The woollen bonnet is thought to have arrived in Scotland through scholars returning home from the centres of learning on the continent during the 16th century. In a country where the weather could change at the drop of a hat, the bonnet was quickly adopted and became an essential item of everyday wear.
The traditional Scots blue bonnet was made famous by the Scottish Covenanters and later by the Jacobite army of John Graham of Claverhouse (‘Bonnie Dundee’).
In the First World War, a khaki Balmoral bonnet was introduced in 1915 for wear in the trenches by Scottish infantry serving on the Western Front. This came to be known as the ‘bonnet, tam o’ shanter’, later abbreviated among military personnel to ‘ToS’. It replaced the Glengarry – which was the regulation bonnet worn by Scottish troops with khaki field dress at the start of the war. Originally knitted, the military tam o’ shanter subsequently came to be constructed from separate pieces of khaki serge cloth.