Cornish Army 

The Cornish Army was first used in combat in 1497, during the Cornish Rebellion. A blacksmith and a lawyer managed to raise an army of 15,000 men and marched into Devon, conquering it, relatively unopposed. Wells, Winchester, Bristol, and Salisbury were taken, though while in Taunton they suffered a slight hiccup when a tax commissioner was murdered, but apart from this one incedent the march was referred to as, 'without any slaughter, violence or spoil of the country'. They tried to rally the 'volatile men of Kent*' to their cause, but the Kentishmen had decided that what was going on was too far away to concern them. This disheartened a number of the Cornish troops, who decided to call it quits and went home. The remainder of the forces decided to take on the King (Henry VII). They arrived at Guildford and awaited the retaliation of the Crown. They were attacked by a meager force of 500 mounted spearmen, which they promptly defeated. The Cornish army then moved in on London and the Royal Family barricaded themselves in the Tower of London, whilst the rest of the city began to panic. At Blackheath the Cornish set up their final camp and prepared for 'The Battle Of Deptford Bridge' (located in south-east London).
The Cornish army had by this point around 12,000 troops, while the King had a whooping 25,000. The battle lasted about half a day and ended with the defeat of the Cornish.
Wouldn't it have been interesting if they had won?

*Home of the Peasants' Revolt of 1381.

The Cornish Army was quite cool... for the 15th Century.

Cornish Army by Emperor Francis I December 9, 2008