Valdemar's military campaigns included conflicts in northern Germany and the establishment of Danish rule in Estonia in 1219.

He was later released upon the initiative of Dagmar of Bohemia (the wife of Duke Valdemar) and Pope Innocent III, after swearing to never interfere again in Danish affairs.

Adolf tried to stir up other German counts to take southern Jutland from Denmark, and to assist Bishop Valdemar's plot to take the Danish throne.

Two years later, due to an illness, Count Adolph was able to buy his way out of prison by ceding all of Schleswig, north of the Elbe, to Duke Valdemar.

In November 1202, Duke Valdemar's elder brother, King Canute VI, unexpectedly died childless.

Valdemar II and the fled capitulars protested to Pope Innocent III, who first wanted to research the case.

In the same year Valdemar II invaded with Danish troops the prince-archiepiscopal territory south of the Elbe and conquered Stade.

In 1211 Duke Bernard III of the younger Duchy of Saxony escorted his brother-in-law Valdemar, the papally dismissed Prince-Archbishop, into the city of Bremen, de facto regaining the See and enjoying the sudden support of Otto IV, who meanwhile fell out with Innocent over Sicily.

The Livonian Knights, who had been attempting to Christianize the peoples of the eastern Baltic, were (by 1219) being hard pressed and turned to Valdemar for help.

When the army landed in Estonia, near modern-day Tallinn, the chiefs of the Estonians sat down with the Danes and agreed to acknowledge the Danish king as their overlord.

At the height of the battle Bishop Sunsen prayed for a sign and it came in the form of a red cloth with a white cross which drifted down from the sky just as the Danes began to fall back.

[7] Count Henry demanded that Denmark surrender the land conquered in Holstein 20 years ago and become a vassal of the Holy Roman Emperor.

[7] To secure his release Valdemar had to acknowledge the break away territories in Germany, pay 44,000 silver marks, and sign a promise not to seek revenge on Count Henry.

Honorius III excused Valdemar from his forced oath, and he immediately set about trying to restore the German territories.

[7] Valdemar concluded a treaty with his nephew Otto I, Duke of Brunswick-Lüneburg and headed south to take back what he thought were his lands by right, but his luck deserted him.

A series of Danish defeats culminating in the Battle of Bornhöved on 22 July 1227 cemented the loss of Denmark's north German territories.

[8] King Valdemar II spent the remainder of his life putting together a code of laws for Jutland, Zealand, and Skåne.

The Code of Jutland (Jyske Lov) was approved at the meeting of the nobility at Vordingborg Castle in 1241, just prior to Valdemar's death there.

Old folk ballads say that on her death bed, she begged Valdemar to marry Kirsten, the daughter of Karl von Rise, and not the "beautiful flower", Berengaria of Portugal (Bengerd).

After Dagmar's death, in order to build good relations with Flanders, Valdemar married Berengária of Portugal in 1214.

She was the orphan daughter of King Sancho I of Portugal and Dulce of Aragon, and a sister of Ferdinand, Count of Flanders, with whom she stayed until her marriage.

Valdemar's two wives played a prominent role in Danish ballads and myths – Dagmar as the soft, pious, and popular ideal wife, and Berengária as the beautiful and haughty woman.