The Monmouth Rebellion of 1685 resulted from the fact that King Charles II, son of Charles I (of English Civil War fame), died without a legitimate heir.
The throne passed to his brother who became King James II. Monnouth was the eldest illegitimate son of Charles II and was persuaded by political factions that the people of England would prefer him to be King rather than James. James was a Catholic and Monmouth a Protestant. The English feared a return to the oppressive Catholic regime of 'Bloody' Queen Mary. Monmouth tried his luck by invading the country at Lyme Regis in June 1685 with only 82 followers.
Monmouth had some initial success, and by the time he reached Taunton had amassed around 6,000men. The men were not, as usually depicted, 'rough ploughmen' but were largely tradesmen or cloth workers. They were, however, mostly untrained raw recruits (Monmouth was hoping the regular army would defect to him). After a setback at Bristol, Monmouth ended up retreating to Bridgwater and eventually trying a desperate night attack across the open moor to catch the Royal army asleep in their tents. It was a close thing but the element of surprise was lost and Monmouth was defeated. The resultant retribution became the well known 'Bloody Assizes' of Judge Jefferies.