The Treaty of Roskilde was negotiated at the parsonage of Høje Taastrup Church and was concluded on 26 February (OS) or 8 March 1658 (NS) in the Danish city of Roskilde during the Second Northern War between Frederick III of Denmark–Norway and Karl X Gustav of Sweden. After a devastating defeat, Denmark–Norway was forced to give up a third of its territory to save the rest, the ceded lands comprising Blekinge, Bornholm, Bohuslän, Scania and Trøndelag, as well as Halland.