Pedzisa mutsara unotevera: Kuti asarudzwe kuva mambo pashure pokufa kwababa vake, Frederick akabvumira vanhu vakakurumbira kuti vave nesimba guru. Samambo, akarwa hondo mbiri neSweden. Akakundwa muHondo yeDano-Swedish ya1657<unk>1658, asi akawana mukurumbira mukuru paakatsungirira hondo yeDano-Swedish ya1657<unk>1658.
1659 Kurwiswa kweCopenhagen uye kukunda Hondo yeDano-Swedish ya1658<unk>1660. Gare gare gore iroro, Frederick akashandisa mukurumbira wake kuparadza umambo hunosarudzwa achitsigira umambo hwakakwana, hwakagara kusvikira muna 1848 muDenmark. Akaroora Sophie Amalie weBrunswick-Lüneburg, waakabereka naye Christian V weDenmark.