1658: The treaty of Roskilde is signed, Bohuslan is lost to Sweden, and Halden becomes a key outpost on the border between Sweden and Norway (then under Danish rule)
1660-1701: Construction of Fredriksten Fortress.
1665: Halden is granted town status.
1716: Halden residents famously set fire to their beloved town to prevent it falling into the hands of King Karl Xll of Sweden and his men.
1718: King Karl XII again tries to take the town, but is killed by a bullet to the head during the siege.
1813: Halden Cotton Spinning Mill, the first mechanised mill in the country, is established, marking the beginning of the industrial era in Norway.
1840s: Extraction of granite in the Iddefjord begins. The quarries and export of Iddefjord granite will play an important role for the town for a century to come.
1928: The town changes its name from Fredrikshald back to Halden.
1940s: During WW2, many local guides help refugees cross the border with neutral Sweden. The (Old) Svinesund Bridge is opened in 1946.
2005: The new Svinesund Bridge is opened.