Canute's fleet set sail for England in the summer of
1015 with a Danish army of 10,000 men, along with support from the allies of Denmark.
Boleslaw the Brave, the
Duke of Poland and relative to the Danish royals, lent some token
Slav troops, likely to have been a pledge made to Canute and Harald when they went to fetch their mother back to the Danish court in the winter of
1014. Sweden's king,
Olof Skötkonung, was a strong ally. He was the son of
Sigrid the Haughty, by her first husband the Swedish king
Eric the Victorious, as well as a relation to the royals of Denmark, by her second husband, the Danish king
Swegen Forkbeard, and the brother of his daughters.
Eiríkr Hákonarson, Canute and Harald's brother-in-law, and
Trondejarl, the
Earl of
Lade, was ruler of Norway, under Swegen, and the sons of Forkbeard, (ref. the
liege and
lord alliance). He was to join Canute once the invasion had been made underway.
Thorkell the High, who actually fought against the Viking invasion under Canute's father with a pledge of allegiance to the English, in
1012, as a Joms chief, was with the fleet, and the Joms too. Some explanation for this particular Jomsviking's, as well as Jomsborg's, shift of allegiance, may be found in a
stanza of the
Jómsvíkinga saga with a statement that two attacks were launched against the Viking mercenaries while they were in England. Also, as if to add insult to injury, amongst their dead soldiers was a chieftain of the Jomvikings known as Henninge, who was a brother to Thorkell the Tall. If it is true that Canute's childhood mentor was indeed this man, here may be the reason for his acceptance of his support, after an opposition against his father's previous expedition. Canute and the
Jomsviking, ultimately in the service of
Jomsborg, were in a very difficult relationship with each other.
Eadric Streona, a nobleman risen far under Ethelred the Unready, his king, to be the wealthy
Earl of Mercia, maybe even the richest of the English nobility, also thought it prudent to join in with Canute, and the Vikings, with forty ships in tow, although these were probably of the
Danelaw anyway. England's king was under pressure, and the distresses which were a fact of his reign, as a man risen to sovereignty through assassination, were apparently too much for many to put up with. In spite of his faults, the Mercian Earl was a useful ally, pivotal to any successes either side might hope for, and he probably knew it. It was though a dangerous game to play in an era with such merciless standards.
Canute was therefore at the head of an epic array of
Vikings, from all over
Scandinavia. Altogether, the invasion force was to be in often close and grisly warfare with the English for the next fourteen months. Most of the battles were fought against
Ethelred the Unready's son,
Edmund Ironside.
In September
1015, Canute was seen off the shore of
Sandwich. The fleet went around the coast about
Kent and the south of England until it came upon the mouth of the
Frome. There the army disembarked and the occupation of
Wessex was begun. Canute had the advantages of surprise and speed, and made a base of the English heartland, with the kingdom in disarray.
A passage from the
Encomium Emmae paints a picture of the scene which was to confront the English, when Canute and his Vikings, within 200 longships had made their landfall:
Until mid-winter the Vikings stood their ground, with the English king held up in London. Canute's invaders then went across the Thames, with no pause in bleak weather, through the
Mercian lands, northwards, to confront
Uhtred, the
Earl of Northumbria, and Edmund Ironside, commander of England's army. Canute found these lands without their main garrisons, as Uhtred was away with Ironside in Mercia, to countermand the properties of Eadric Streona.
Northumbria fell, and when Uhtred returned to sue for peace, Canute executed the Earl for breaking oaths pledged to Sweyn Forkbeard two years earlier. Canute brought over
Eiríkr Hákonarson and strategically put the Norwegian in control of Northumbria, while he strengthened his army with the reserves.
In April
1016, Canute went southward with his army through the western
shires to gain as much support from the English as possible, already confident in the eastern
Danelaw. The Viking fleet set sail for the
Thames to lay
London under siege.
Edmund Ironside was effectively swept before this onslaught, which left London as his last stronghold.
Ethelred the Unready died on April 23, coincidentally, leaving the now beleaguered prince as king. Over the next couple of months the attackers made their camps on the city's fringes, and dug a canal through which to pull their ships and cut off the supply lines up river. Encirclement was made complete by the construction of dikes on the city's northern and southern sides. Also forays on the walls were frequent.
In the summer, Edmund Ironside broke out of London to raise an army in Wessex, and the Vikings broke off a portion of their siege in pursuit. The English rallied at
Penselwood; with a hill in
Selwood Forest as the likely location of their stand. The battle that was fought there did not leave any clear victor. A subsequent battle at
Sherston in
Wiltshire was fought over two days and again left neither side victorious.
Edmund Ironside did eventually end the siege of London. With the Scandinavians in disarray, Canute brought the forces back together in
Wessex and the besiegers again focused their attentions on the city of London. However, the English resistance was such that the invaders had to make their way north into
Mercia to search for essential supplies.
At this point Eadric Streona thought it wise to ally himself with the English again. Vikings were subsequently put under attack in Mercia, and the army of Edmund Ironside forced the besiegers of London back to their ships on the
Isle of Sheppey in
Kent. The fleet went north and the invasion force reassembled in
Essex. Here in October at Assandun, on the hill of ash trees, the two armies came together for one final confrontation. Canute won the
Battle of Ashingdon decisively, partly because the Earl of Mercia betrayed his countrymen when he and his men retreated in the heat of battle.
Edmund Ironside, probably wounded, was caught near
Wales and the
Forest of Dean, where there was likely to have been a final struggle made in an attempt by the English to protect their king. Canute was ultimately able to force peace talks.
Canute and Ironside met on an island in the
Severn. Edmund accepted defeat, signing a treaty with the Viking king in which all of England, except for Wessex was to be controlled by the Scandinavians. Its key clause was that when one of the two kings should die, the other king would be the one and only king of England, his sons being the heirs. It was a move of astute political sense, as well as mercy, on the part of Canute. After Edmund's death, on November 30,
1016, possibly at the hands of the traitor Eadric Streona's men, or more probably as a result of his wounds, Canute ruled the whole kingdom. His coronation was at Christmas, with recognition by the nobility in January 1017.
It was at the coronation that the untrustworthy Eadric Streona was decapitated, his head being mounted on a pole. This execution was by the hand of Erikr,
Earl of Northumbria. It is uncertain whether Canute chose to execute Eadric to dissociate himself from the dishonour of the former king's murder, or simply for disloyalty. It was not possible for the Crown to be seen to tolerate treachery. Canute was to be one of England's most successful kings, ultimately achieving a wide unity across Scandinavia and the North Atlantic.
