A few years later Christian IV wielded his influence in order to provide his third-born son Frederick and Ulrik with prebendaries in Lutheran-ruled prince-bishoprics within the Holy Roman Empire.

In 1622 Ulrik received a canonicate at Bremen Cathedral chapter, where his brother Frederick had been appointed as coadjutor in September 1621, a function usually including the succession to the see.

He had endowed her with the manor and estates of Zibühl (a part of today's Dreetz in Mecklenburg) as her allodial dower, which he had bought for 17,000 rixdollars in 1621.

Meanwhile, Ulrik attended Sorø Academy, and in 1627 he was enfeoffed with the prior Schleswig-episcopally Schwabstedt manor and estates with its revenues, which also had belonged to his uncle.

In support of his maternal uncle Christian IV, King Charles I of England, Ireland, and Scotland had sent English and Scottish mercenaries, who stood in the western Schleswig marshes.

He then travelled via Glückstadt again to the Dutch Republic, fighting under Stadtholder Frederick Henry, Prince of Orange in his Siege of 's-Hertogenbosch until its surrender on 14 September 1629.

In the same time Christian IV tried a rapprochement with Emperor Ferdinand II and Wallenstein in order to regain Schwerin and Verden for his deposed sons.

Meanwhile, Swedish Lutheran troops had conquered the Catholic-occupied Prince-Bishopric of Schwerin, so that Ulrik hoped to regain his realm from Gustavus Adolphus.

In Denmark Ulrik recruited a cuirassier company under his command, and – in summer – he joined with it the electoral Saxon army under Hans Georg von Arnim-Boitzenburg for Silesia.

During the war efforts, interrupting the negotiations, Ulrik excelled again, inflicting the imperial Croatian riders a significant defeat.

On 11 August 1633, during one of these meetings in Schweidnitz, he was fatally wounded by an unexpectedly treacherous shot from an imperial horseman, and died the following night.

After a funeral, it was then brought to Copenhagen, where it was set up in the Church of Our Lady, until his mortal remains found their final rest in Christian IV's chapel in Roskilde Cathedral in 1642.

In addition to being brave, Ulric was characterised as having extensive knowledge of languages and literary interests, besides some small talent for drawing, painting, music and recitation of poems.

In June 2010, Jacob van Doort's portrait of Duke Ulrik was brought back to Denmark due to a donation from the Augustinus foundation.

The painting had been positively identified as being a childhood portrait of Duke Ulrik by Professor Steffen Heiberg who has written several books about King Christian IV and his reign.