Fredriksten Fredriksten is a fortress in the city of Halden in Norway . History . This Fortresses was constructed by Denmark - Norway in the 17th century as a replacement for the border fortress at Bohus , which had been lost when the province of Bohuslän was ceded to Sweden by the terms of the Treaty of Roskilde in 1658 . The fortress was named after King Fredrik III of Denmark and Norway , and the town of Halden was also originally named after him , having been known as " Fredrikshald " between 1665 and 1928 . The Northern War ( 1655 – 1661 ) . At the close of the Northern War Charles X , having negotiated the Treaty of Roskilde in bad faith , invested Copenhagen in August 1658 . Under his orders , in September the new Swedish governor of Bohuslän invaded Norway with 1 , 500 men and attempted to invest Halden . The inhabitants put up a vigorous defense and the Swedish forces retreated back to Bohuslän . Five months later in February 1659 the Swedes again attacked . Since their first attack , the garrison had been strengthened . Under the leadership of Tønne Huitfeldt the Norwegian forces again repulsed the Swedish forces . Concurrently , Huitfeldt began construction of fortifications . Cretzenstein , later to be renamed Fredriksten , was the citadel of the new fortification system . In early January of 1660 , the Swedish forces attacked Halden for the third time ; it was to serve as the base for their advance on Akershus fortress in Christiania . Huitfeldt responded to their demand that they surrender , that the 2 , 100 man garrison would defend Halden to the last man . After the attempt to storm the fortifications was unsuccessful , the Swedes prepared a regular siege . Under heavy bombardment the inhabitants requested the commandant to surrender , but putting his faith in his garrison , Huitfeldt held out . On 22 February 1660 the Swedes again were forced to retreat to Bohuslen . There they learned that Charles X had died . Peace negotiations were reopened . Sweden demanded that Norway vacate all land east of the river Glomma , which was to serve as the new border . With the intercession of Hannibal Sehested , a separate Scandinavian treaty was negotiated which improved on the terms of the Treaty of Roskilde , returning Trøndelag to Norwegian control . Fortification Upgrades ( 1673 – 1675 ) . The existing star shaped fortress complex was upgraded during the period of peace between 1661 – 1675 . In 1673 Denmark dispatched Ulrik Frederik Gyldenløve as statholder to Norway to organize the military forces and strengthen the defenses of the kingdom . After a tour of facilities , he recommended further upgrades to both the fortress and the military forces . In the summer of 1675 , 1800 men were kept at work on the fortresses at Akershus , Fredrikstad , and Fredrikshald . Gyldenløve War ( 1675 – 1679 ) . At the outbreak of the Gyldenløve War in 1675 a large contingent ( 4000 men ) were concentrated at Fredrikshald under General Russenstein . In 1676 Norwegian troops reoccupied Bohuslän . In July 1677 Gyldenløve captured the fortress at Marstrand and joined General Løvenhjelm , who marched into Bohuslen with the main Norwegian army and defeated an army of 8000 Swedes under General de la Gardie . A Norwegian force also retook Jämtland , but withdrew again as ordered by the King . No major defensive activities were needed at Fredriksten as no Swedish forces crossed the frontier . Fortification Upgrades ( 1679 – 1700 ) . Fredriksten was expanded from 1682 – 1701 . It now included three outer fortifications : Gyldenløve , Overberget and Stortårnet . Great Northern War ( 1700 – 1721 ) . At the close of the Great Northern War , the Norwegian Army had been weakened in early 1716 by withdrawal of 5000 of the best troops to Denmark . When rumors reached Christiania that Charles XII was preparing to invade , all remaining troops in Østerdal and Gudbrandsdal were ordered to the border at Halden and Fredrikstad . The Norwegians expected the Swedes to invade at Kongsvinger , Basmo and / or Halden . It was at Basmo where Charles XII struck , crossing the border on 8 March 1716 . The Norwegian scorched earth policy and guerrilla raid interdiction of supply chains by the residents of Bohuslen deprived Charles of supplies , while the fortresses still held by the Norwegians behind his lines threatened his supply chain and his retreat if seriously weakened in combat . Charles took Christiania ( now Oslo ) , but without heavy siege artillery , was unable to take Akershus . After a brief occupation , Charles retraced his steps to the Norwegian fortresses in southeastern Norway with the objective of capturing Frederiksten . This would remove the threat at his back , and the fortifications could serve as the base for a renewed offensive later that year . Capturing the harbours at the mouth of the Glomma river would also allow him to land the necessary provisions for a successful siege of Akershus . Charles ' troops attempted to take Frederiksten by storm on 4 July . His troops took the town after fierce fighting , but the citizens set fire to their own houses , forcing Charles , unable to take the fortress , to retreat and await the arrival of heavy siege guns . Unfortunately for the invading army the entire Swedish transport fleet was captured or destroyed by the Norwegian naval hero Tordenskjold at the Battle of Dynekilen in Bohuslen . Running low on supplies , Charles retreated hastily across the Svinesund and burned the bridges behind him . By 12 July 1716 all Swedish troops had been withdrawn from the area around Fredriksten . In the Autumn of 1718 Charles once more attacked Norway , intending to first capture Halden to be able to sustain a siege of Akershus . By first taking the border areas , Charles wished to avoid a repeat of the fiasco he had suffered two years before . The 1 , 400 strong garrison of Frederiksten fought ferociously to hold back the invasion , but suffered a severe setback when , on 8 December the forward fortification Fort Gyldenløve fell . Encouraged by their very hard - fought success the Swedish army intensified their efforts against the main fort . The Swedish trenches had almost reached the main fortification walls when on the evening of 11 December ( Swedish calendar : 30 November ) 1718 , a bullet struck and killed Charles XII while he inspected the work . The death of the king effectively ended the attack on Fredriksten and the invasion was called off , leading to the conclusion of the war . A memorial is located in the park named in his memory where the Swedish king fell , just in front of the fortress . 1788 . The fortress served as a staging area for a mock attack on Sweden during the Theater War . 1814 . The fortress was bombarded but not captured . The advancing Swedish forces of Charles John passed it on their advance , leaving a force that tried to force its surrender , but the fortress and its commander kept the ground . It was turned over to Sweden after the Convention of Moss . The old fortress flag from 1814 , taken by the Swedish troops and not returned to Norway until 1964 , is preserved in the present day museum located inside the inner fortress . The fortress today . After 1905 the fortress lost all military significance , but it still hosted various units . As of today the Norwegian defence logistics and administrative college is situated by the fortress . The fortress also hosts several museums and art exhibitions . During the summer season outdoor concerts are arranged with both classic and contemporary music .