The Battle of Aclea occurred in 851 between the West Saxons led by Æthelwulf, King of Wessex and the Danish Vikings at an unidentified location in England (noted by near-contemporaries as being in Surrey).
Little is known about the battle and the most important source of information comes from the Anglo-Saxon Chronicle which recorded that: Aclea means Oak Field, as Asser explained.
If the Vikings followed Stane Street (Chichester) south from London Bridge, the only crossing over the Thames into the area covered by modern-day Surrey during the early medieval period, they would have come to the gap in the North Downs and passed through in the direct of Dorking.
Asser defines Surrey, rather vaguely, as "a district which is situated on the southern bank of the River Thames, to the West of Kent" - the River Thames running all the way from the east coast of England to west of Swindon.
Though located within the modern-day borders of the county of Hampshire, rather than in Surrey, there is evidence to suggest that a now-forgotten battle had taken place near Oakley at some point, including numerous tumuli and several early medieval skeletons buried underneath the floor of a local church.