Key dates in the history of Somerset

• 43–47 – Roman invasion and occupation
• 491 – Battle of Mons Badonicus (may have been fought in Somerset) (uncertain date)
• 537 – Battle of Camlann (sometimes located at Queen Camel) (uncertain date)
• 577 – Battle of Deorham (Dyrham, Gloucestershire) – Saxons occupied Bath
• 658 – Battle of Peonnum (Penselwood ?) – Saxons then occupied most of Somerset
• 710 – Battle of Llongborth (? Langport)
• 845 – First documentary reference to "Somersæte"
• 878 – Battle of Cynwit – Saxon victory over the Danes by Ealdorman Odda
• 878 – Battle of Ethandun – West Saxon victory over the Danes (uncertain whether in Somerset or Wiltshire)
• 878 – Treaty of Wedmore – after defeat of Danes by King Alfred the Great
• c900 – Kings of Wessex hold court at Cheddar
• 973 – King Edgar of England crowned at Bath
• 988 – St Dunstan buried at Glastonbury
• 1013 – Danish king Sweyn Forkbeard received submission of western thegns at Bath
• 1088 – Siege of Ilchester
• 1191 – Discovery of "King Arthur's" tomb at Glastonbury
• 1497 – Perkin Warbeck's rebellion supported by Somerset men
• 1643 – Battle of Lansdowne
• 1645 – Siege of Taunton during the English Civil War
• 1685 – Battle of Sedgemoor – Duke of Monmouth defeated
• 1685 – Judge Jeffries holds the "Bloody Assizes" at Taunton
• 1770 – Start of major enclosures of Somerset Levels
• 1805 – Somerset Coal Canal Opened
• 1827 – Bridgwater and Taunton Canal opened
• 1875 – Formation of Somerset County Cricket Club
• 1898 – County boundaries altered
• 1956 – Chew Valley Lake opened by Queen Elizabeth II
• 1974 – Formation of County of Avon, reducing the area of the County of Somerset
• 1996 – Abolition of the County of Avon, creating the unitary authorities of North Somerset and Bath and North East Somerset