Early fortifications of Sweden were built to defend self-governing provinces, with rapid expansion of forts in the 14th century and again later in the 16th century, when Sweden became independent and needed to protect its borders.
Changes in the position of borders led to fortifications changing owner, to and from Sweden; some became redundant; and a few forts were given major upgrades for improved technology over the centuries.
12C
13C
14CHundred Years' War and Black Death
15CUnification under one king and expansion of territory with first Union with Norway and Denmark
16CSweden gains independence and Protestant Reformation, Livonian War, creation of Sweden's first professional army.
17CIngrian War, Kalmar War, Thirty Years' War and Second Northern War saw Swedish territory expand.
18CAfter Swedish defeats in the Great Northern War as well as in the Russo-Swedish War of 1741-1743, there was a need to construct fortifications to guard both the border as well as the coast of Finland.
19CUnion with Norway after Norway ceded to Sweden by Denmark[1]
20CDissolution of the union between Norway and Sweden, neutral in First and Second World Wars. Cold War era.
[‡] Currently in use by the Swedish Military