develop by the 12th century. Charters from the period refer to the town's trade in iron, and to forges making use of local ore and charcoal. The cinders produced by the forges formed heaps, and were used in building foundations; the name of Cinderhill Street in Overmonnow dates from this period. During the period of turmoil between the supporters of King Henry III and the barons who sought to curtail his power, the town was the scene of a major battle in 1233, in which the king's forces were routed by the troops of Richard Marshal, Earl of Pembroke. Later, the castle was extended by Henry's son Edmund Crouchback, after he became Earl of Lancaster in 1267. In about 1300, town walls were built, and the bridge over the Monnow was fortified. The bridge, now pedestrianised, remains in place today, the only such fortified bridge in Britain and reputedly one of only three similar crossings in Europe. King Edward II was briefly imprisoned at Monmouth Castle in 1326 after being overthrown by his wife Isabella and her lover Roger Mortimer, the Earl of March. In the mid 14th century, the castle and town came into the possession of the House of Lancaster through the marriage of John of Gaunt to Blanche of Lancaster. John of Gaunt strengthened the castle, adding the Great Hall, and the castle became a favourite residence of the House of Lancaster. In 1387, John of Gaunt's grandson was born to Mary de Bohun, in the Queen's Chamber within the gatehouse of Monmouth Castle, while his father Henry Bolingbroke was hunting in the area. The boy was known as Henry of Monmouth before his coronation as Henry V; supported by longbowmen from the area, he won the Battle of Agincourt in 1415. Monmouth's links with Henry are commemorated in the naming of the main town square, Agincourt Square, and in the statue of Henry on the front of the Shire Hall. From the 14th century onwards, the town became noted for the production of woollen Monmouth caps. However, as a border town, its prosperity suffered after nearby areas, including Usk and Grosmont, were devastated through attacks by supporters of Owain Glyndŵr around 1405, though Monmouth itself did not come under attack. Post-medieval times In 1536, Henry VIII imposed the Laws in Wales Acts 1535–1542, abolishing the powers of the Marcher Lords and integrating the administration of England