Lewes (Derivation: possibly OE; hlæwas = burial mounds) is the county town of East Sussex, about 8 km (5miles) from the coast at Brighton. It dates from Anglo-Saxon times but these days is dominated by the keep of Lewes castle, built about 1100. The town's aspect has been called “well-preserved Georgian”.
The Battle of Lewes: it was outside Lewes that, on 14 May 1264, a baronial force led by Simon de Montfort 6th earl of Leicester defeated royalist forces almost double its size and captured Henry III and two of his sons Edward and Richard. Simon's position on higher ground after a night march and Edward's mistake in pursuing part of Simon's force in retreat, instead of remaining on the field of battle, contributed greatly to the outcome. Simon became the effective ruler of England until his death at the Battle of Evesham the next year.
Reference: “Brewer’s Britain and Ireland”