The following account is from Roger of Wendover: 

“A few days after this lamentable battle (Assingdun), in which so many nobles fell, King Edmund pursued Canute, who was now committing ravages in Gloucestershire.  The said kings therefore came together to fight at a place called Deerhurst, Edmund with his men being on the west side of the river Severn, and Canute with his men on the east, both preparing themselves manfully for battle.  When both armies were now on the point of engaging, the wicked Earl Edric called together the chiefs and addressed them as follows:  ’Nobles and warriors, why do we foolishly so often hazard our lives in battle for our kings, when not even our deaths secure to them the kingdom, or put an end to their covetousness?  My counsel then is, that they alone should fight who alone are contending for the kingdom; for what must be the lust of dominion, when England, which formerly sufficed for eight kings, is not now enough for two?  Let them, therefore, either come to terms, or fight alone for the kingdom.’  This speech pleased them all; and the determination of the chiefs being communicated to the kings, received their approbation.  There is a small island called Olney, in the mouth of that river.  Thither the kings, clad in splendid armour, crossed over, and commenced a single combat in the presence of the people.  Parrying the thrust of the spear as well by their own skill as by the interposition of their strong shields, they fought long and fiercely hand to hand, his valour protecting Edmund, and his good fortune Canute.  The swords rung on their helmets, and sparks of fire flew from their collision.  The stout heart of Edmund was kindled by the act of fighting, and as his blood grew warm his strength augmented; he raised his right hand, brandished his sword, and redoubled his blows on the head of his antagonist with such vehemence, that he seemed rather to fulminate than to strike.  Feeling his strength failing him, and unable long to endure such an onset, Canute meditated peace; but as he was crafty, and afraid lest if the youth perceived his weakness he would not listen to his words of peace, drawing in all his breath he rushed on Edmund with wonderful valour, and immediately drawing back a little, he asked him to pause awhile and give him audience.  The latter was of a courteous soul, and, resting his shield on the ground, he listened to the words of Canute, who thus proceeded:  ’Hitherto I have coveted thy kingdom, bravest of men; but now I prefer thyself not only to the kingdom of England, but to all the world.  Denmark serves me, Norway yields me subjection, the King of Sweden has shaken hands with me; so that, although Fortune promises me victory everywhere, yet thy wonderful manliness hath so won my favour, that I long beyond measure to have thee as friend and partner of my kingdom.  I would that thou in like manner wert desirous of me; that I might reign with thee in England, and thou walk me in Denmark.’  Why should I add more?