Oehlenschläger and his sister Sofia were allowed their own way throughout their childhood, and were taught nothing, except to read and write, until their twelfth year. At the age of nine, Oehlenschläger began to make fluent verses. Three years later, while walking in Frederiksberg Gardens, he attracted the notice of the poet Edvard Storm, and the result of the conversation was that he received a nomination to the college called Posterity's High School, an important institution of which Storm was the principal. Storm himself taught the class of Scandinavian mythology, and thus Oehlenschläger received his earliest bias towards the poetical religion of his ancestors.
Oehlenschläger was confirmed in 1795, and was to have been apprenticed to a tradesman in Copenhagen. To his great delight there was a hitch in the preliminaries, and he returned to his father's house. He now, in his eighteenth year, suddenly took up study with great zeal, but soon again abandoned his books for the stage, where he was offered a small position. In 1797 he made his appearance on the boards in several successive parts, but soon discovered that he possessed no real histrionic talent. The brothers Ørsted, with whom he had formed an intimacy that proved quite profitable to him, persuaded him to quit the stage, and in 1800 he entered the University of Copenhagen as a student. He was doomed, however, to disturbance in his studies, first from the death of his mother, next from his inveterate tendency towards poetry, and finally from the First Battle of Copenhagen in April 1801, which, however, inspired a dramatic sketch (April the Second 1801) which is the first thing of the kind by Oehlenschläger that we possess.
In the summer of 1802, when Oehlenschläger had an old Scandinavian romance, as well as a volume of lyrics, in the press, the young Norse philosopher, Henrik Steffens, came back to Copenhagen after a long visit to Schelling in Germany, full of new romantic ideas. His lectures at the university, in which Goethe and Schiller were revealed to the Danish public for the first time , created a great sensation. Steffens and Oehlenschläger met one day at Dreier's Club, and after a conversation of sixteen hours the latter went home, suppressed his two coming volumes, and wrote at a sitting his splendid poem Guldhornene, in a manner totally new to Danish literature. The result of his new enthusiasm speedily showed itself in a somewhat hasty volume of poems, published in 1803, now chiefly remembered as containing the lovely piece called Sanct Hansaften-Spil.
The next two years saw the production of several exquisite works, in particular the epic of Thors Reise til Jotunheim, the charming poem in hexameters called Langelandsreisen, and the bewitching piece of fantasy Aladdin (1805). At the age of twenty-six, Oehlenschläger was universally recognized, even by the opponents of the romantic revival, as the leading poet of Denmark. He now collected his Poetical Writings in two volumes. He found no difficulty in obtaining a grant for foreign travel from the government, and he left his native country for the first time, joining Steffens at Halle in August 1805. Here he wrote the first of his great historical tragedies, Hakon Jarl, which he sent off to Copenhagen, and then proceeded for the winter months to Berlin, where he associated with Humboldt, Fichte, and the leading men of the day, and met Goethe for the first time.
In the spring of 1806 he went on to Weimar, where he spent several months in daily intercourse with Goethe. The autumn of the same year he spent with Tieck in Dresden, and proceeded in December to Paris. Here he resided eighteen months and wrote his three famous masterpieces, Baldur hin Gode (1808), Palnatoke (1809), and Axel og Valborg (1810).
In July 1808 he left Paris and spent the autumn and winter in Switzerland as the guest of Madame de Staël-Holstein at Coppet, in the midst of her circle of wits. In the spring of 1809 Oehlenschläger went to Rome to visit Bertel Thorvaldsen, and in his house wrote his tragedy of Correggio. He hurriedly returned to Denmark in the spring of 1810, partly to take the chair of aesthetics at the University of Copenhagen, partly to marry the sister-in-law of Rahbek, to whom he had been long betrothed. His first course of lectures dealt with his Danish predecessor Johannes Ewald, the second with Schiller. From this time forward his literary activity became very great; in 1811 he published the Oriental tale of Ali og Gulhyndi, and in 1812 the last of his great tragedies, Stærkodder.
From 1814 to 1819 he, or rather his admirers, were engaged in a long and angry controversy with Baggesen, who represented the old didactic school. This contest seems to have disturbed the peace of Oehlenschläger's mind and to have undermined his genius. His talent may be said to have culminated in the glorious cycle of verse-romances called Helge, published in 1814. The tragedy of Hagbarth og Signe, (1815), showed a distinct falling-off in style. In 1817 he went back to Paris, and published Hroars Saga and the tragedy of Fostbrødrene. In 1818 he was again in Copenhagen, and wrote the idyll of Den lille Hyrdedreng and the Eddaic cycle called Nordens Guder. His next productions were the tragedies of Erik og Abel (1820) and Væringerne i Miklagaard (1826), and the epic of Hrolf Krake (1829). His last volumes were Tordenskjold (1833), Dronning Margrethe (1833), Sokrates (1835), Olaf den Hellige (1836), Knud den Store (1838), Dina (1842), Erik Glipping (1843), and Kiartan og Gudrun (1847). On his seventieth birthday, November 14, 1849, a public festival was arranged in his honor, and he was decorated by the king of Denmark under circumstances of great pomp. He died on January 20, 1850, and was buried in the cemetery of Frederiksberg. Immediately after his death his Recollections were published in two volumes.
In 1829 he was publicly crowned with laurel as the "king of Nordic poetry" and the "Scandinavian King of Song" (by Bishop Esaias Tegnér, who would be his Swedish parallel) in the cathedral of Lund, Sweden, based on a vast production of poetry, theatre plays and prose, inspired by Johann Wolfgang von Goethe, Gottlieb Fichte, and Friedrich von Schelling. (See also Jens Immanuel Baggesen)