Question: Which battle to which Æthelwulf of Berkshire lost his life was a battle on 4 January 871 at Reading in what is now the English county of Berkshire?

Context paragraphs:
Battle of Ashdown: The Battle of Ashdown, in Berkshire (possibly the part now in Oxfordshire), took place on 8 January 871.  Alfred the Great, then a prince of only 22, led the army of his brother, King Ethelred of Wessex, in a victorious battle against the invading Danes.

Kentwood (Reading ward): Kentwood is an electoral ward of the Borough of Reading, in the English county of Berkshire.  It consists of the northern part of the suburb of Tilehurst, in the west of Reading, south of the River Thames.  The ward is bordered by Mapledurham and Battle wards to the east, and Norcot and Tilehurst wards to the south.  To the west the ward is bordered by the reduced civil parish of Tilehurst in the district of West Berkshire which is the remainder of the larger ancient parish, before the expansion of the Borough of Reading.  The ward has schools and churches bearing a Tilehurst, rather than Reading name.

Æthelwulf of Berkshire: Æthelwulf of Berkshire (before 825 – 4 January, 871) was a Saxon ealdorman.  In 860 he and other men of Berkshire fought off a band of pirates near Winchester, Hampshire.  Later he mustered a force of 1400 men against an army of Danes, won the 31 December 870 Battle of Englefield on behalf of the then kingdom of Wessex.  He received a land grant in 843/44 from Brihtwulf, king of Mercia; and lost his life at the Battle of Reading.

Battle of Englefield: The Battle of Englefield was a battle on 31 December 870 at Englefield, near Reading in what is now the English county of Berkshire.  It was one of a series of battles, with honours to both sides, that took place following an invasion of the then kingdom of Wessex by an army of Danes, during which the Danes had established a camp at Reading.  Both battle and campaign are described in the "Anglo-Saxon Chronicle".

Tilehurst: Tilehurst is a suburb of the town of Reading in the English county of Berkshire.  It lies to the west of the centre of Reading, and extends from the River Thames in the north to the A4 road in the south.  The suburb is partly within the boundaries of the Borough of Reading and partly in the district of West Berkshire.  The part within West Berkshire forms part of the civil parish of Tilehurst, which also includes the northern part of Calcot and a small rural area west of the suburb.  The part within the Borough of Reading includes the Reading electoral wards of Tilehurst and Kentwood.

Katesgrove: Katesgrove is an inner-town district near the centre of the town of Reading in the English county of Berkshire and ward of the Borough of Reading, in the English county of Berkshire.  It is bounded on the north by the Inner Distribution Road and Reading town centre, on the east by Sidmouth Street, London Road, Kendrick Road and Northumberland Avenue, on the west Coley Park and Southcote, on the south by Long Barn Lane and Rose Kiln Lane and on the west by the River Kennet.

Battle of Reading (871): The first Battle of Reading was a battle on 4 January 871 at Reading in what is now the English county of Berkshire.  It was one of a series of battles, with honours to both sides, that took place following an invasion of the then kingdom of Wessex by an army of Danes led by Bagsecg and Halfdan Ragnarsson in an attempt to conquer Wessex.  Both battle and campaign are described in the "Anglo-Saxon Chronicle", and this account provides the earliest known written record of the existence of the town of Reading.

BBC Radio Berkshire: BBC Radio Berkshire is the BBC Local Radio service for the English county of Berkshire, North Hampshire, and South Oxfordshire.  Radio Berkshire broadcasts on 94.6 (Henley-on-Thames), 95.4 (Windsor), 104.1 (Hannington) and 104.4 (Reading) FM from its studios at Caversham Park near Reading.  The station is also available on DAB, Freeview, and through live streaming on the internet, also on demand for thirty days after broadcast through the BBC iPlayer.

Royal Berkshire Hospital: The Royal Berkshire Hospital is a National Health Service hospital in the town of Reading in the English county of Berkshire.  It provides acute hospital services to the residents of the western and central portions of Berkshire, and is managed by the Royal Berkshire NHS Foundation Trust.

Battle of Basing: The Battle of Basing was a battle on 22 January 871 at Old Basing in what is now the English county of Hampshire.  It was one of a series of battles that took place following an invasion of the then kingdom of Wessex by an army of Danes.  Both battle and campaign are described in the "Anglo-Saxon Chronicle".

Supporting paragraphs: Æthelwulf of Berkshire Battle of Reading (871)
Answer: Battle of Reading