Ulf's assistance to Cnut at the Battle of the Helgeå has not caused Cnut to forgive Ulf for his coup.

At a banquet in Roskilde, the two brothers-in-law are playing chess and start arguing with each other.

The next day, Christmas of 1026, Cnut has one of his housecarls kill Earl Ulf in Trinity Church, the predecessor of Roskilde Cathedral.

Accounts are contradictory, however.

Ulf is the father of Sweyn Estridson, and thus the progenitor of the House of Estridsen, which will rule Denmark from 1047 to 1375, and which is also sometimes, specially in Swedish sources, referred to as the Ulfinger dynasty to honor him.

Eric II, having dispatched Harald Kresla and most of his sons, now seeks to consolidate and legitimize his rule over Denmark.

He awards titles and privileges to his supporters, and proclaims Archbishop Asser's nephew as Bishop Eskil of Roskilde.

Eric is defeated in 1135 in a naval battle near the coast of Denmark, and Slavs under duke Ratibor I, Duke of Pomerania, sack Roskilde.

Eric, on learning that Eskil has raised the nobles of Zealand against him, races north to put down the rebellion, which had spread rapidly across Funen and Jutland, and fines Eskil heavily.

Olaf Haraldsen, after trying in vain to regain his heritage, proclaims himself king in Scania in 1139, fighting his cousin King Eric III of Denmark.

The civil war mostly consists of alternating raids, during which Olaf kills Bishop Rike of Roskilde, an act that sees him excommunicated by the Pope.

Sweyn III, son of Eric Emune, had been declared king of Zealand and Scania after Eric III of Denmark abdicated in 1146, while Canute, son of king Magnus, had become king of Jutland.

Canute had made several attempts to conquer Zealand (1147 and 1150), but was driven off and fled to Germany, where he had managed to raise an army.

A battle had been fought in 1152 at Gedebæk, close to Viborg.

Canute had lost and appealed to the German king (later emperor), Frederick I Barbarossa, who commanded both kings to meet him at Merseburg.

Here, Frederick had confirmed Sweyn's rights of kingship, and Sweyn had sworn fealty to him.

The nobles of Denmark were growing concerned about the growing German influence.

Valdemar, having at first joined Sweyn, who had made him duke of Schleswig, changed sides and was betrothed to Canute's half-sister Sophie.

Both Canute and Sweyn had been hailed as kings in 1154 at the Landsting in Viborg.

The three contenders had  agreed to share power, so that Valdemar would rule Jutland, Canute would rule the islands of Zealand and Funen, and Sweyn would rule Scania.

A reconciling feast is agreed upon, and it is held in Roskilde on August 9, 1157, where, according to Saxo Grammaticus, Sweyn ordered his men to kill the two other kings.

Canute is slain, but Valdemar, though wounded, managed to turn over some great candlesticks and escape in the following fire and confusion.

He flees in the darkness and manages to return to Jutland.

Canute IV forces Bogislaw to acknowledge Canute as his overlord in 1185.

From thais time until 1972, the Kings and Queens of Denmark will use the title "King of the Wends" as part of a lengthy list of duchies, counties, and regions ruled by Danish monarchs through the centuries.

Margaret of Denmark, born in March 1353 as the sixth and youngest child of Valdemar IV of Denmark and Helvig of Schleswig, had been baptized in Roskilde and in 1359 as a six-year-old engaged to the eighteen-year-old King Haakon VI of Norway, the youngest son of the Swedish-Norwegian king Magnus IV & VII.

As part of the marriage contract it is presumed that a treaty is signed that obligates King Valdemar to assist Magnus in a dispute with his second son, Eric "XII" of Sweden, who in 1356 had been hailed as king there and had been given dominion over Southern Sweden.

Margaret's marriage is thus a part of the Nordic power struggle.

There is dissatisfaction with this in some circles, and the political activist Bridget of Sweden describes the agreement in a letter to the Pope as "children playing with dolls".

The goal of the marriage for King Valdemar is regaining Scania, which since 1332 had been mortgaged to Sweden.

The capital of Denmark is transferred in 1416 from Roskilde, located in northeastern Denmark on the Roskilde Fjord, to …

…Copenhagen, about twenty miles (thirty-two kilometers) to the east.

Roskilde, named for Hroar (Ro), its legendary founder, and for springs (kilde) of the region, is dominated by its enormous cathedral, consecrated in the fifteenth century, which is the burial place of many of the country's kings and queens.

The rebellion against Eric of Pomerania, the king of the Kalmar Union, led by Swedish nobleman Engelbrekt Engelbrektsson in 1434-1436, results in the deposing of Eric as well as erosion of the union.