Commonly used to describe the Napoleonic era British foot soldiers, the British Regular was known for his flamboyant red uniform (It took three hours for a typical British soldier to prepare his attire for "parade") and well-disciplined combat performance. Known famously in American folklore as the Red Coats, these crack soldiers were the backbone of Great Britain's military might in the eighteenth and nineteenth centuries.
There are several possible reasons why the British military outfitted its Regulars in red. The most commonly stated reason is that it would hide the appearance of blood on the battlefield, possibly demoralising the troops. This is unlikely because blood would show black on the red cotton tunics, and the white, or "buff" trousers that were commonly issued would hide no blood at all. Another possible explanation would be that red dye was extremely cheap, allowing the Army to give its troops better equipment without wasting money on more expensive dyes. Another good reason could be that British officers needed to be able to identify their men in heavy smoke. Red would show better through gunsmoke than most other colours. A final possibility is that red is the primary colour in the Royal Standard, the Royal Coat of Arms, and is the colour of St George's cross (St George is the patron saint of England).
During the Napoleonic Wars, the British Regulars were already a well disciplined, and experienced group of foot soldiers. Around half of the British Regular "Redcoats", most were between the ages of 18 to 29; and an over sixth-tenths of the regulars were five feet, four inches, to five feet seven inches. The British Government at the time, did not allow enlisted men to be older than 45 years old.
Although under British command, many of the the enlisted Regulars were either Scottish or Irish. A small number of Regulars were from Prussia, or other smaller German states. From these multiple origins, also came into two different "Schools of Thought"; The 'American' thought, and the 'German' thought.
The American thoughts consisted of large focus on open formations light infantry tactics that were well suited for areas of rigid terrain, and dense forested areas; best suited for enemies that have no cavalry, or artillery to use. The 'American' favoured infantry ranks of two deep, and use of light infantry with rifles. The German thoughts consisted of a large focus on disciplined, close-drill order, well suited for the vast Central Plains of Europe. The thought was more favourable in large battlefields, were the enemy had large to mild amounts of cavalry, and artillery on the battlefield. The 'German' School of thought favoured infantry ranks of three deep, and the use of smoothbore muskets.
After 1855, starting in India and gradually extending to other colonial outposts, the scarlet uniforms were often replaced with khaki on campaign - for tactical reasons (ie camouflage). However, not until 1902, and the introduction of a universal khaki service dress, would scarlet be officially abandoned as campaign dress for European operations. The classical British Regular was most famous for his action in the Battle of Culloden, the Seven Years' War (1756-1753), the American Revolutionary war (1775-1783), the Peninsular War (1808-1815), the War of 1812 (1812-1814), and the Waterloo campaign (1815).