Florence of Worcester’s genealogies name "Ælfgiva, comitis Ægelberhti filia" as mother of King Æthelred’s three sons "Eadmundum, Eadwium et Æthelstanum" and his daughter "Eadgitham". Roger of Wendover records the birth in 981 of "rex Ethelredus…filium…Eadmundum", but this date is probably inaccurate if it is correct...that Eadmund was his father’s third son, given King Æthelred’s birth in . "Eadmundus filius regis/clito/ætheling" subscribed charters of King Æthelred II dated between 993 and 1015, the last dated 1015 being signed "Eadmund regie indolis soboles". His name was listed after his brother Ecgberht, before the latter's disappearance from the records in 1005, consistent with Edmund being the third son. He subscribed his father's charter dated 1002 which granted land at Codicote, Hertfordshire to Ælthelm, signing third among the brothers, and "Eadmundus clito" subscribed his father's 1006 charter making grants to St Alban's, also signing third. Ætheling Æthelstan, under his will dated , made bequests to "…my brother Eadmund, my brother Eadwig…". After the murder of the brothers Sigeferth and Morcar, leading thegns in northern England, Edmund abducted and married Sigeferth's widow against his father's wishes. In Sep 1015, he proceeded north to retake the properties of his wife's first husband which had been confiscated by the king.
In early 1016, Edmund devastated northwest Mercia in alliance with Uhtred Earl of Northumbria, but returned to London to rejoin his father shortly before he died. He was immediately proclaimed king on his father's death in 1016 by an assembly of northern notables and burghers of London, succeeding as EDMUND "Ironside" King of England, crowned at Old St Paul's Cathedral in Apr 1016. The Witan had offered the throne to Knud of Denmark, to whom a group of nobles and church dignitaries from southern England swore allegiance at Southampton. King Edmund reconquered Wessex from Danish forces, and relieved London from the siege imposed by a Danish fleet. The Danes turned their attention to Mercia, Eadric "Streona/the Acquisitor" defecting back to King Edmund's forces at Aylesford only to betray him again at Ashingdon in Essex where Danish forces finally defeated King Edmund in Oct 1016.
At Alney, near Deerhurst, Edmund agreed a compromise division of the country with Canute, Edmund taking Wessex and Canute the north, but King Edmund died before this could be implemented. The Anglo-Saxon Chronicle records the death on St Andrew's day 1016 of King Edmund and his burial at Glastonbury. According to Henry of Huntingdon, King Edmund was murdered by the son of Eadric Streona.
Ældgyth, widow of Sigeferth, daughter of --- . The Anglo-Saxon Chronicle records that "prince Edmund…abducted [Siferth's widow] against the king's will and made her his wife" but does not name her. Simeon of Durham records that Edmund married "Algitha widow of Sigeferth" in 1015. According to Ronay, she was the daughter of Olof "Skotkonung" King of Sweden and his concubine Edla of Vindland, but the author cites no primary source to support this suggestion. If the assertion is correct, it is surprising that Ældgyth is not mentioned with the Swedish king's other children in the Saga of Olaf Haraldson. In addition, there would be no explanation for Ældgyth's first marriage to an obscure Northumbrian nobleman, especially as King Olof's two known daughters made high-profile marriages with the Grand Prince of Kiev and the king of Norway. Simeon of Durham records that, after Ældgyth's first husband was murdered on the orders of Eadric "Streona/the Acquisitor" Ealdorman of Mercia, Ældgyth was arrested and brought to Malmesbury on the orders of King Æthelred II who had confiscated her husband's properties in the north of England. She was abducted and married, against the king's wishes, by her second husband who proceeded to take possession of her first husband's properties. No mention has been found of Queen Ældgyth after the death of her second husband. 1