The extension of Danish influence among the Wends brought Denmark into closer contact and relations with the Empire. Two years after Canute's expedition to the Slavic lands, Henry the Saint passed to his reward, and Conrad the Salic succeeded to the imperial dignities. On the death of Henry II. the great Polish Duke Boleslav hastened to assume the regal title, and evidently planned to renounce the imperial suzerainty. This policy of hostility to the Empire was continued by his son and successor, Mieczislav, who also may have hoped to interest his cousin King Canute in the welfare of the new kingdom.
Conrad also felt the need of a close alliance with the Danish conqueror, and called upon Archbishop Unwan of Hamburg-Bremen for assistance as a mediator. Unwan was Canute's friend and succeeded in bringing about the desired understanding. Possibly the price of the alliance may have appealed to Canute as much as the Archbishop's arguments; for Conrad bought the friendship of his Northern neighbour with the Mark of Sleswick to the Eider River.[223]
The exact date of this alliance is a matter of doubt, but the probabilities appear to favour 1025, when the Emperor Conrad was in Saxony. Some historians believe that the mark was not ceded at this time but ten years later, when Canute's daughter Gunhild was betrothed to Conrad's son Henry, as Adam of Bremen seems to associate these two events.[224] But Adam's chronology is confused on these matters. Canute's friendship was surely more difficult to purchase in 1025 when his star was rapidly ascending than in 1035 when his empire had begun to collapse. While we cannot be sure, it seems extremely likely that the boundary of Denmark was extended to the Eider in 1025.
FOOTNOTES:
[192] Langebek, Scriptores, i., 159 (note).
[193] Anglo-Saxon Chronicle, 1018.
[194] Simeon of Durham, Opera Omnia, i., 216. The account of the siege of Durham is not by Simeon but by some writer whose identity is unknown.