The Battle of Lewes, 14 May 1264, saw the army of Simon de Montfort, earl of Leicester (d.1265), defeat that of King Henry III (d.1272). It was the first battle of the Second Barons’ War, otherwise known as England’s First Revolution, which saw the Montfortians seize the reins of power from the king and set up a council to rule in his stead, with the help of parliament.

By 13 May, the king’s forces were camped at Lewes, those under his eldest son and heir, Edward, at the Castle, and those with the king at the Priory, a little to the south of the town; meanwhile the Montfortians were camped in woodland to the north of the town between Offham and Hamsey. The last attempt at negotiations broke down and both sides prepared for battle.

In the early hours of 14 May, Simon de Montfort led his army to the crest of the hillside to the west of Lewes, to a site named Boxholte, where they were signed with the cross as crusaders. His army was then set in four divisions: the right commanded by Simon’s sons Henry and Gui, with John de Burgh and Henry de Bohun; the left comprised men raised from the city of London, commanded by Nicholas of Segrave and Henry of Hastings; the centre was led by the earl of Gloucester, Gilbert de Clare, together with John fitz John and William de Munchensey. Simon de Montfort himself commanded the reserve, which would be crucial in the battle.

The king’s forces significantly outnumbered Simon’s, though it is impossible to be certain of the numbers involved: Henry perhaps had as many as 1,500 mounted knights, with perhaps 2-3,000 foot soldiers. On seeing the Montfortian army arrayed on the hillside above the town offering battle, the royalists hastily assembled into three divisions: the king commanded the left, with the right led by Edward, and the centre by Richard earl of Cornwall, the king’s brother.

The advantage of terrain was with the Montfortians, with Henry's troops being obliged to attack uphill. Edward’s division clashed with the Londoners and put them to flight, and Edward and his men unwisely chased them from the field, perhaps as far as four miles. At this point, Simon de Montfort brought in his reserves and the Montfortians were able to push the royal troops back down the hill to the town, where fighting continued in the streets. Henry took refuge in the Priory, where Edward was eventually able to join him. Negotiations continued throughout the night, and ended with Henry, Edward, and Richard of Cornwall surrendering themselves as prisoners.

The victory allowed the Montfortians to establish a new revolutionary government, with a council of nine ruling the kingdom, aided by parliament. The regime was finally brought down at the Battle of Evesham, 4 August 1265.

A battlefield walk leaflet, which the Battlefields Trust helped to produce, is available from the Lewes Tourist Information Centre.