It is a survivor of the felt hats worn by 18th century armies. At varying periods since then the slouch hat has been worn by military personnel from many nations including Australia, Britain, India, New Zealand, France, the United States, Germany and many others, but Australia had a slouch as the standard issue head wear from around 1885, and still does to this day. Today, it continues to be worn by military personnel from a number of countries, although it is primarily associated with Australia, where it is considered to be a national symbol. The distinctive Australian slouch hat, sometimes called an Australian bush hat , has one side of the brim turned up or pinned to the side of the hat with a special badge (the bayonent collection badge, or the rising sun badge) in order to allow a rifle to be slung over the shoulder. In the United States it was also called the Kossuth hat, after Lajos Kossuth. See http://howardlanham.tripod.com/linkgr4/link198.html.
A contemporary painting dated 1884 (in the regimental museum) of the pipe band of 1st Battalion Argyll & Sutherland Highlanders in service dress, crossing the veldt in Zululand, shows them wearing khaki slouch hats. A shortage of cork helmets led to the widespread use of the slouch hat amongst British Empire forces during the Second Boer War Dennis et al 2008, p. 497. , where it was used by units such as the City Imperial Volunteers (CIV), Imperial Yeomanry, and King Edward's Horse. After the war, however, many armies rejected the once-popular headwear (as the British Army did in 1905), although it came back into fashion briefly during World War II during the Burma campaign and amongst troops serving in India and Southeast Asia at this time. Brayley 2002, pp. 2532.
A Unit Colour Patch is also worn by members of the Australian Army on their Slouch Hat to indicate which unit they are from.
The 2nd Gurkha Rifles became the first Gurkha regiment to adopt the slouch hat when they were issued with the Australian variant in 1901. The Gurkha terai hat is created by fusing two hats into one to make the hat more rigid and is worn at an angle, tilted to the right.
On 22 December 1890, the military commanders of the then separate Australian Colonies prior to the Federation of Australia met to discuss the introduction of the khaki uniform throughout Australia. They agreed that all Australian Forces with the exception of the Artillery would wear the slouch hat. It was to be looped up on one side Victoria and Tasmania on the right and the other colonies (later states) on the left. Grebert 1997.
The Australian slouch hat (also known as a Hat KFF, or Hat Khaki Fur Felt) is worn with a seven band puggaree, said to represent the six states and the territories of Australia. For the Army, the hat includes the soldiers' Unit Colour Patch Australian Army unit colour patches [1] (right of puggaree), Corps or Regiment Hat badge (front of puggaree) and the General Service Badge (The Rising Sun, affixed on the left brim) on both the Grade 1 and Grade 2 Slouch Hats. When on ceremonial parades, e.g. ANZAC Day, the Slouch Hat is worn with the brim up (Grade 1), showing the General Service Badge on the left side. However, when the soldier's dress of the day is either DPCU's or Polys, then they wear the hat with the brim flat (Grade 2). The term "Polys" is a colloquialism used in the Australian Defence Force to refer to a soldier's formal uniform (as opposed to disruptive pattern camouflage uniform. This formal uniform is made partially from polyester, hence the term.
The RAAF & RAN Slouch Hats do not have unit colour patches, nor do they wear it brim up; instead the only badge worn is the RAAF or RAN cap badge, of a design appropriate to the wearer's rank, at the front of puggaree.
Local tailors made a slouch hat in a style between a French type bush hat of the First Indochina War and an Australian type bush hat with a snap on the brim to pin one side up that was widely bought and unofficially worn by American troops in Vietnam. The local tailors usually used green fatigue cloth or leopard skin pattern military camouflage from old parachutes. The hat often had a cloth arc emblazoned with the word VIET-NAM on the brim. The U.S. 1st Air Commando Group members adopted the green slouch hat as their distinctive and practical headgear with an AIR COMMANDO arc.
Karnataka Police continues to use slouch hats for its members in the lower rungs of the police force (Constables and Head Constables). The slouch hat will have the colours of the police unit embroidered on the brim which is put up. The police number of the officer is also fixed onto this side of the brim.
Source: Wikipedia > Slouch Hat
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