King Æthelred of Wessex, and his brother and successor, Alfred, the first English monarch to plan systematically for the defense of his realm against the Danish Vikings, war with them from 871, winning a victory at the Battle of Ashdown, in Berkshire (possibly the part now in Oxfordshire), at the beginning of the year.

Accounts of the battle are based to a large extent on Asser's "Life of Alfred", however there is some dispute about whether this is an authentic account.

Two Viking armies, the established force in East Anglia and a fresh army from Denmark, overrun eastern Britain in 871, the “Year of Battles,”and settle at Reading, situated on the River Kennet, thirty-nine miles (sixty-three kilometers) west of London.

The English forces of King Æthelred and Alfred engage the Reading-based Viking armies as they advance toward Wessex, driving them back to their camp.

Attacking the Vikings there, the West Saxons incur heavy losses and are forced to withdraw.

Alfred, the younger son of the late King Æthelwulf, in April 871 succeeds his brother Æthelred as king of Wessex.

Alfred, now king of Wessex, attacks in late 871 near Wilton after a series of inconclusive skirmishes between the Danish Vikings and the West Saxons.

The Danes feign a retreat in a successful ploy to draw an attack, and are victorious.