bring about their withdrawal in 877. A portion of the Danish army settled in Mercia, but at the beginning of 878 the remaining Danes mounted a winter invasion of Wessex, taking Alfred by surprise and overrunning much of the kingdom. Alfred was reduced to taking refuge with a small band of followers in the marshes of the Somerset Levels, but after a few months he was able to gather an army and defeated the Danes at the Battle of Edington, bringing about their final withdrawal from Wessex to settle in East Anglia. Simultaneous Danish raids on the north coast of France and Brittany occurred in the 870s – prior to the establishment of Normandy in 911 – and recorded Danish alliances with both Bretons and Cornish may have resulted in the suppression of Cornish autonomy with the death by drowning of King Donyarth in 875 as recorded by the Annales Cambriae. No subsequent 'Kings' of Cornwall are recorded after this time, but Asser records Cornwall as a separate kingdom from Wessex in the 890s. In 879 a Viking fleet that had assembled in the Thames estuary sailed across the channel to start a new campaign on the continent. The rampaging Viking army on the continent encouraged Alfred to protect his Kingdom of Wessex. Over the following years Alfred carried out a dramatic reorganisation of the government and defences of Wessex, building warships, organising the army into two shifts which served alternately and establishing a system of fortified burhs across the kingdom. This system is recorded in a 10th-century document known as the Burghal Hidage, which details the location and garrisoning requirements of thirty-three forts, whose positioning ensured that no one in Wessex was more than a long day's ride from a place of safety. In the 890s these reforms helped him to repulse the invasion of another huge Danish army – which was aided by the Danes settled in England – with minimal losses. In 2015, two individuals found a large hoard near Leominster consisting primarily of Saxon jewellery and silver ingots but also coins; the latter date to around 879 CE. According to a news report, "experts believe it [the hoard] was buried by a Viking during a series of raids known to have taken place in the area at that time", while Wessex was ruled by Alfred the Great and Mercia by Ceolwulf II. Two imperial coins recovered