803 - The Synod of Clofeshoh (possibly Brixworth) is held, at which the Archbishopric of Lichfield is demoted to an ordinary Bishopric, with Papal permission obtained by King Coenwulf of Mercia.

806 - King Erdwulf of Northumbria is expelled from his kingdom by one Aelfwald who takes the throne as King Aelfwald II. Erdwulf flees to the Imperial Frankish Court of Charlemagne and later visits Pope Leo III in Rome.

807 - Death of King Cuthred of Kent. Kent possibly under direct Mercian rule.

808 - With the active support of Emperor Charlemagne of the Franks and Pope Leo III, the exiled King Erdwulf of Northumbria is able to return to his kingdom and oust the usurper, King Aelfwald II.

809 - The Papal Legate is kidnapped by Vikings while sailing for Northumbria.

c.810 - Death of King Erdwulf of Northumbria. He is succeeded by his son, Enred. Canterbury Cathedral is probably demolished by Archbishop Wulfred of Canterbury and rebuilt on a more extravagant basilican scale

c.812 - King Sigered of Essex is reduced to the rank of Dux by his Mercian overlords.

818 - King Coenwulf of Mercia raids Dyfed.

821 - King Coenwulf of Mercia dies in Basingwerk, while preparing for another assault on Powys, and is buried in Winchcombe Abbey. His son, Cenelm, is chosen to succeed him, but he is killed, probably fighting the Welsh, though supposedly through the treachery of his jealous sister, Cwenthryth. He is also buried at Winchcombe Abbey and later revered as a saint. The Mercian throne passes to Coenwulf's brother, Ceolwulf I. One Aethelstan makes a push for the East Anglian throne, but is halted by Ceolwulf I of Mercia.

823 - The Mercians invade Powys, but are beaten back by King Cyngen. They also destroy the Gwynedd capital, Degannwy. Death of King Ceolwulf I of Mercia. He is succeeded by Beornwulf, a descendant of the late King Beornred. Rise of King Baldred of Kent. His allegiance is uncertain, but he was probably a relative of King Beornwulf of Mercia. Aethelstan of East Anglia attempts to claim the East Anglian throne again.

825 - King Egbert of Wessex defeats the mighty Mercians at the Battle of Ellandon. He invades Kent and expels King Baldred. The former's son, Aethwulf, is installed as King of Kent. The sub-Kingdoms of Essex, Sussex and Surrey submit to Egbert. The Mercians are allowed to retain Berkshire and its boundaries are formally set. Aethelstan of East Anglia begins to re-assert East Anglian independence. King Beornwulf of Mercia invades East Anglia, but is killed in battle. He is succeeded by one Ludecan. The men of Cornish Dumnonia clash with the Saxons of Devon at the Battle of Gafelford (Camelford or Galford). First written record of the county of Devon in the Saxon form of the name.

827 - Aethelstan of East Anglia establishes himself as King of that country after killing King Ludecan of Mercia in battle. Ludecan is succeeded in Mercia by Wiglaf, father-in-law (and probably distant cousin) of the late King Ceolwulf I's daughter.

828 - King Egbert of Wessex is recognized as overlord of other English Kings. He overruns Mercia, ousts King Wiglaf and attempts to rule directly from Wessex.

829 - King Enred of Northumbria and King Egbert of Wessex clash at the Battle of the River Dore. Supposed submission of Northumbria to Wessex overlordship.

830 - King Wiglaf regains control of Mercia from Wessex.

832 - Northumbrian Lothian is attacked by King Angus II of the Scots & Picts. He defeats the superior forces of Prince Aethelstan at Battle of Aethelstaneford.

c.833 - Rise of a Dux Sigeric II of Essex under Mercian patronage.

835 - The Isle of Sheppey comes under Viking attack.

836 - The army of King Egbert of Wessex is defeated by invading Vikings at the Battle of Carhampton.

838 - The British of Dumnonia join forces with the Vikings and attack Wessex. King Egbert defeats them at the Battle of Hingston Down.

839 - Death of King Egbert of Wessex & All England. His son, King Aethelwulf of Kent succeeds as King of Wessex. Aethelwulf's brother, Aethelstan, is made sub-King of Kent, Essex, Surrey and Sussex. Death of King Aethelstan of East Anglia. He is succeeded by one Aethelweard.

840 - Viking raids turn away from Britain as the Frankish Empire is weakened by the Death of Emperor Louis the Pious. Death of King Wiglaf of Mercia. He is buried at Repton and briefly succeeded by his grandson, Wigstan. King Wigstan prefers the religious life and asks his widowed mother, Princess Aelfflaed to act as regent. A noble of the line of the late King Beornred, named Berhtric, wishes to marry this lady, but as he is a relative, Wigstan refuses the match. Berhtric murders Wigstan at Wistow. He is buried at Repton and later revered as a saint. The Mercian throne is seized by Berhtric's father, Bertwulf. First written record of the county of Dorset.

841 - Death of King Enred of Northumbria. He is succeeded by his son as King Aethelred II.

844 - King Aethelred II of Northumbria is expelled from the kingdom by one Redwulf, who takes the throne. King Redwulf is later killed in battle against the Vikings, along with many of his noblemen, during a major raid. King Aethelred II returns.

845 - The ship of King Ragnar Lothbrok of Sjaelland & Uppsala (Scandinavia) is supposedly blown off course and he lands in East Anglia. He is entertained at the Royal Court but internal politics leads to him being kidnapped and smuggled into Northumbria where he is executed in a pit of vipers. Glastonbury Abbey is probably damaged by Viking raiders. Ealdorman Enwulf of Somerset defeats them at the Battle of the River Parrett. First written record of the county of Somerset.

c.846 - King Aethelred II of Northumbria sends military assistance to the Picts in their fight against invading Scots.

848 - Assassination of King Aethelred II of Northumbria. He is succeeded by Osbert, of unknown lineage.