Battle of Assandun The Battle of Assandun 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 was a victory for the Danes , led by Canute the Great ( Cnut , Knut or Knud ) , who triumphed over the English army led by King Edmund II ( ' Ironside ' ) . The battle was the conclusion to the Danish reconquest of England . In earlier times , what is now England had been seven kingdoms ; by the late 900s there were two . The Danes ruled two - thirds of England , the Danelaw : the area north of the Thames , along the Lee , northwest through the midlands including eastern Mercia to Chester and the River Dee . The Saxons ruled the area south of the Thames , the west - Wessex and western Mercia . In response to Edmund ' s reconquest of recently Danish - occupied Wessex and to various indecisive offensives against Canute ' s army , Canute besieged London with major support from the English nobility , particularly the Southampton nobles , against the Saxon hierarchy . London withstood the siege and Edmund repulsed the Danes , but needed troops following a successful attack against the Danes in Mercia . Leaving London , Edmund risked travelling into the countryside , which was dominated by enemies and where he was in danger of being attacked by Danish soldiers . Canute ' s intelligence became aware of Edmund ' s movements and while marching through Essex Edmund ' s army was intercepted by Canute . The surprise interception overwhelmed the English , causing some of them to desert , and the Danes poured on the English , killing much of the nobility . Some sources claim that the Danes were losing ground , and that Eadric Streona had previously made a deal with Canute to desert the other English forces . Following his defeat , Edmund was forced to sign a treaty with Canute . By this treaty , all of England except Wessex would be controlled by Canute and when one of the kings should die the other would take all of England , that king ' s son being the heir to the throne . After Edmund ' s death on 30 November , Canute duly ruled the whole kingdom directly . Thus for the first time England became a single united kingdom , covering the same territory as it does today . Canute was accustomed to building a church , chapel or holy site after winning a battle to commemorate the soldiers who died in battle . A few years later in 1020 the completion took place of the memorial church known as Ashingdon Minster , on the hill next to the presumed site of the battle in Ashingdon . The church still stands to this day . Canute attended the dedication of Ashingdon Minster with his bishops and appointed his personal priest , Stigand , to be priest there . The church is now dedicated to Saint Andrew but is believed previously to have been dedicated to Saint Michael , who was considered a military saint : churches dedicated to him are frequently located on a hill . There is another possible location of the battle ; Ashdon , also in Essex . There have been many finds of Roman and Anglo - Saxon coins in the area . Historians have argued inconclusively over the two sites for years . There is some strong evidence : a couple of Anglo - Saxon wills that definitely show Ashdon as the battle site . Also , the 10th century wooden village church , itself possibly built on the site of a pre - Christian temple , was probably rebuilt in stone in the early 11th century , about the right time for Canute ' s conquest . Unfortunately little remains of the earlier structures , which were largely obliterated by the construction of the current church of All Saints during the late 13th to early 15th centuries . Primary sources . The " Anglo - Saxon Chronicle " has a brief account of the battle . The battle is also mentioned briefly in " Knýtlinga saga " which quotes a verse of skaldic poetry by Óttarr svarti , one of Canute ' s court poets . The most detailed account of the battle is in " Encomium Emmae " .