Question: Who was the King of England from 23 April to 30 November 1016 that also led the English army in the Battle of Assandun?

Context paragraphs:
Battle of Clitheroe: The Battle of Clitheroe was a battle between a force of Scots and English knights and men at arms which took place on 10 June 1138 during the period of The Anarchy.  The battle was fought on the southern edge of the Bowland Fells, at Clitheroe, Lancashire.  It took place in the course of an invasion of England by King David I of Scotland.  In the summer of 1138, King David split his army into two forces.  One of them, commanded by William fitz Duncan, Mormaer of Moray, marched into Lancashire.  There he harried Furness and Craven.  On 10 June, William fitz Duncan was met by a force of knights and men-at-arms.  A pitched battle took place and the result was that the English army was routed.  The battle was a prelude to the Battle of the Standard later in the summer, where the result was reversed.

Ordinance of Normandy: The Ordinance of Normandy is the name given to a paper authored by Philip VI of France on 23 March 1338.  It called for a second Norman conquest of England, with an invading army led by the Duke of Normandy, and England was to be divided between the Duke of Normandy and his nobles as a fief for the King of France.  It was discovered by the English army at Caen, following the Battle of Caen in 1346 that ensued from the English invasion of Normandy.  The Earl of Huntingdon brought the document to England after he was invalided home and it was read out in St. Paul's Cathedral in London by the Archbishop of Canterbury, John de Stratford.  It was claimed that King Philip vowed to "destruire & anientier tote la Nation & la Lange Engleys" [destroy and eliminate the entire English nation and language].  However some scholars believe the letter to have been forged.

Battle of Haddon Rig: The Battle of Hadden Rig was a battle fought about 3 miles east of Kelso, in the Scottish Borders, between Scotland and England on 24 August 1542, during the reign of King James V of Scotland.  The English army was led by Robert Bowes, Deputy Warden of the English East March.  It was a significant Scottish victory, but it was overshadowed by the disastrous Scottish defeat at the Battle of Solway Moss in November.

Edmund Ætheling: Edmund Ætheling ( ;  1015–17 – possibly 1046, certainly by 1054) was a member of the royal House of Wessex as the son of Edmund Ironside, who briefly ruled as King of England between April and November 1016.  He fought the Danish Vikings under Cnut the Great, but following the Danish victory at the Battle of Assandun in October, it was agreed that Ironside would rule Wessex, while Cnut took Mercia and probably Northumbria.  In November 1016, Ironside died and Cnut became King of all England.

Edmund Ironside: Edmund II (died 30 November 1016), usually known as Edmund Ironside, was King of England from 23 April to 30 November 1016.  He was the son of King Æthelred the Unready and his first wife, Ælfgifu of York.  Edmund's reign was marred by a war he had inherited from his father, his cognomen "Ironside" was given to him "because of his valour" in resisting the Danish invasion led by Cnut the Great.

Battle of Assandun: The Battle of Assandun (or Essendune) was fought between Danish and English armies on 18 October 1016.  There is disagreement whether Assandun may be Ashdon near Saffron Walden in north Essex or, as long supposed, Ashingdon near Rochford in southeast Essex, England.  It ended in victory for the Danes, led by Canute the Great, who triumphed over the English army led by King Edmund Ironside.  The battle was the conclusion to the Danish reconquest of England.

Battle of Brunanburh (poem): The Battle of Brunanburh is an Old English poem.  It is preserved in the "Anglo-Saxon Chronicle", a historical record of events in Anglo-Saxon England which was kept from the late ninth to the mid-twelfth century.  The poem records the Battle of Brunanburh, a battle fought in 937 between an English army and a combined army of Scots, Vikings, and Britons.  The battle resulted in an English victory, celebrated by the poem in style and language like that of traditional Old English battle poetry.  The poem is notable because of those traditional elements and has been praised for its authentic tone, but it is also remarkable for its fiercely nationalistic tone, which documents the development of a unified England ruled by the House of Wessex.

Battle of Flodden: The Battle of Flodden or Flodden Field, or occasionally Battle of Branxton (Brainston Moor), was part of a conflict between the Kingdom of England and the Kingdom of Scotland.  The battle was fought in Branxton in the county of Northumberland in northern England on 9 September 1513, between an invading Scots army under King James IV and an English army commanded by Queen Catherine of Aragon.  It was a decisive English victory.  In terms of troop numbers, it was the largest battle fought between the two kingdoms.  James IV was killed in the battle, becoming the last monarch from the island of Britain to suffer such a death.

Battle of Stamford Bridge: The Battle of Stamford Bridge took place at the village of Stamford Bridge, East Riding of Yorkshire, in England on 25 September 1066, between an English army under King Harold Godwinson and an invading Norwegian force led by King Harald Hardrada and the English king's brother Tostig Godwinson.  After a bloody battle, both Hardrada and Tostig along with most of the Norwegians were killed.  Although Harold Godwinson repelled the Norwegian invaders, his army was defeated by the Normans at Hastings less than three weeks later.  The battle has traditionally been presented as symbolising the end of the Viking Age, although major Scandinavian campaigns in Britain and Ireland occurred in the following decades, such as those of King Sweyn Estrithson of Denmark in 1069–1070 and King Magnus Barefoot of Norway in 1098 and 1102–1103.

Æthelred the Unready: Æthelred II, also dubbed the Unready (Old English: Æþelræd, ] ), (  966 – 23 April 1016) was King of the English (978–1013 and 1014–1016).  He was the son of King Edgar the Peaceful and Queen Ælfthryth and was around 12 years old when his half-brother Edward the Martyr was murdered on 18 March 978.  Although Æthelred was not personally suspected of participation, the murder was committed at Corfe Castle by his attendants, making it more difficult for the new king to rally the nation against the military raids by Danes, especially as the legend of St Edward the Martyr grew.

Supporting paragraphs: Battle of Assandun Edmund Ironside
Answer: Edmund Ironside