of Mochrum, at Flodden. In 1526 the position was made hereditary to the Maxwells (later Earls of Nithsdale). In 1542, Robert Maxwell was captured after the battle of Solway Moss, and forced to hand Threave over to the English invaders. It was retrieved for Scotland by the Earl of Arran in 1545. The Catholic Maxwell family, based at Caerlaverock Castle, were often suspected of treachery as Scotland turned to Protestantism, and Lord Maxwell was required to surrender Threave temporarily as the Spanish Armada approached the English coast. During the Bishops' Wars of 1638–1640, the Maxwells supported Charles I. A garrison of up to 100 men was installed at Threave, and further earthworks were added to the Castle's defences. The army of the Covenanters, opposed to the royalist cause, arrived in summer 1640 and laid siege to the castle. After holding out for 13 weeks, the garrison surrendered on the orders of King Charles. The Covenanters ordered the buildings to be dismantled, and the materials to be disposed "to the use of the public". Later history The keep and artillery house largely remained standing, but Threave was never lived in again. Around 1800, during the Napoleonic Wars, modifications were made to allow French prisoners to be held there, although it is not recorded that Threave was actually used for this purpose. In 1913 the ruins were given into state care, and some repairs and archaeological investigations were carried out. The castle has been a scheduled monument since 1921 due to its national significance. More detailed excavations took place in the 1970s, revealing details of the castle's history. Threave Castle is cared for by Historic Environment Scotland and is open to the public. Access to the castle is via a boat over the River Dee, from the Threave Estate, which is owned by the National Trust for Scotland and operated as a nature reserve that is home to bats and ospreys. Castle Threave Castle comprises a 14th-century keep or tower house, and an outer wall that includes the 15th-century artillery house. It is sited on the western edge of the island, which today covers , although in the 15th century it is estimated to have been only a third of this size. The island would have supported subsidiary buildings, such as stores and workshops, as well as the castle. Access was by boat or via a ford or underwater causeway at the