Denmark-Norway, Saxe-Poland-Lithuania and Russia had agreed on invading the Swedish Empire on three fronts, and accordingly, Danish forces moved into Holstein-Gottorp,[2] allied and dynastically tied to Sweden,[3] and laid siege to Tönning in March 1700.

[2] The siege had to be lifted when Charles XII of Sweden, backed by the Maritime Powers, in a surprise move deployed an army in front of Copenhagen, forcing Frederik IV of Denmark-Norway out of the war by the Peace of Travendal on 18 August 1700.

[6] In February 1713, breaching his proclaimed neutrality,[7] the minor duke Charles Frederick of Holstein-Gottorp[8] provided Stenbock with shelter and auxiliaries at his fortress of Tönning in anticipation of support by the Maritime Powers, expecting a recurrence of the 1700 precedent.

[10] Danish forces, in pursuit of a royal occupation order of 13 March 1713,[7] gained complete control over Holstein-Gottorp when the last Holsteiners loyal to Sweden were captured in 1715.

[11] The decision of the duke of Holstein-Gottorp to open Tönning to Stenbock as well as the brokering of the Swedish surrender is ascribed to baron Georg Heinrich von Görtz, a diplomat at Charles Frederick's court.