King of Denmark and Norway, son of Cristian IV, born in Haderslev on 18 March 1609 and died in Copenhagen February 9, 1670. He was elected by the States to succeed his father in 1648 and was proclaimed King, while the following year, as all his predecessors had done, he signed a capitulation to the nobility, that his powers were depleted from the previous. During the first years who was seated on the throne was dedicated to the exaltation of his country, but then made war to Sweden, intending to recover the territories ceded before his coronation. Despite the sorry state of the army and the little cash available to him, he declared the war and began a disastrous campaign for the Danes; in 1657 he attacked Sweden, which was fighting against Poland, but was defeated and lost Scania, Halland, Bornholm and for the peace of Roskilde Trondheim; but, in 1658, his armies came to camp at the foot of the ramparts of Copenhagen and, thanks to the Treaty signed two years later in the Danish capital, the territories of Bornholm and Trondheim were reinstated him.
After the war, Federico decided to convene a diet in Copenhagen to study measures that partly addressing the damage caused by the war. In 1660 he met in that city and signed a treaty, under which the tax and legislative powers that had been until then in the hands of the nobility, was laid with what the Administration lived a certain resurgence; that same year he was invested with absolute power, and the hereditary monarchy was voted. He was succeeded by his son Cristian V.