Sweyn II Estridsen would end up fathering sixteen sons, of which five would sit on the throne: Harald III, Canute IV, Olaf I, Eric I, and Niels.

[6] He was also a strong candidate for being the next king, as he enjoyed support from the powerful house of Hvide, who raised him, and from Holy Roman Emperor Lothair III, who granted him the title Duke of Holstein for his campaigns against the Wends.

[11] Soon after, civil war broke out when Canute Lavard's half-brother, Eric II, gathered his late brother's levies to avenge him.

This was all a ruse, however, as King Niels was able to gather the support of the Jutlandic nobles, and rout the forces of Eric completely at the Battle of Jellinge Heath.

[13] Lothair III marched north with an army of 6000 men, joined by a naval force under Eric to relieve the city of Schleswig from a siege.

During the ensuing battle, Lothair deserted after coming to an agreement with Magnus and Niels in which they agreed to pay a large sum of money and abandon Lund as an independent archdiocese and place it under Hamburg-Bremen.

[15] Despite these heavy defeats, the continued support of the nobles of Zealand, such as the Hvides and Peder Bodilsøn,[16] would cause figures such as the Archbishop of Lund, Asser Thorkilsson, as well as several members of the Jutish nobility, to swing over to Eric II's side.

Eric's navy then raided along the Limfjord, landing many troops around Himmerland and sacking Viborg, where the local bishop Eskild– a supporter of Niels– was murdered during his morning service in the year 1132.

Fortunately for him, some German merchants in Roskilde aided in crafting siege weapons, and Eric would employ trebuchets for the first time in Scandinavian history, finally breaking through and butchering the garrison.

However, Archbishop Asser, still ignorant of Niels' deal with the Holy Roman Emperor, convinced the Scanians to finally desert Eric who went into exile in Norway.

[23] At the Battle of Fodevig, on the second day of Pentecost 1134, Niels, Magnus the Strong and Harald Kesja, all co-kings with an enormous army at their backs landed on the Fotevik, in a daring amphibious assault.

Contemporary chroniclers highly disagree about the personality of Eric III, and he is portrayed both as a passive and irresolute man, as well as an eager and brave fighter.

[34] In 1147, Canute and Sweyn called a truce so they could participate in the Wendish Crusade, but they returned early after being defeated by Niklot soon after landing.

An agreement was made to divide Denmark into three kingdoms: Valdemar was to have Jutland, Canute was to have Funen, and Sweyn was to have Zealand and Skåneland.

They met at the Battle of Grathe Heath where Valdemar's much smaller force defeated Sweyn, who according to legend, was killed by an angry peasant while fleeing.