[2] Niels and Magnus aimed to take control of Jutland to secure the southern border and the Danevirke, and to this end they defeated Eric at Jellinge Heathe.

Eric, quickly recuperating from his earlier defeat, gathered his navy and sailed for his half-brothers capital of Schleswig, which commanded the crossing of the Danevirke.

Magnus the Strong came first, he quickly manned the Dannevirke, had the dikes expanded, ordered wooden palisades built, together with other defensive works,[3] Eric, who arrived shortly after, only had naval superiority and so had no real way of dislodging his foes.

Lothair promised future aid, however, and Eric managed to convince Adolf II of Holstein to stay, likely committing to a joint attack.

[4] Eric's had attempted breakthrough also failed miserably, and with his forces completely defeated, he decided to hunker down for the winter, with any hope of holding onto Schleswig lost.

Asser Thorkilsson, the Archbishop of Lund, later learned of the secret provision of the treaty subjugating his Archdiocese to Bremen, and as a result would switch sides and play a pivotal role in Eric's eventual victory.