From 1850 onwards it was again repaired and strengthened at great cost, and was considered impregnable; but in the war of 1864 the Prussians turned it by crossing the Schlei, .and it was abandoned by the Danes on the 6th of February without a blow.
It is situated at the west end of the long narrow arm of the sea called the Schlei, 30 m.
Long, forming a semicircle round the Schlei, and is divided into the old town (Altstadt), Holm, Lollfuss, and Friedrichsberg.
Between Friedrichsberg and Lollfuss on an island between the Schlei and Burg See is the old château of Gottorp, now used as barracks.
The former commercial importance of the town has disappeared, and the Schlei now affords access to small vessels only.
The town or bay of the Slia or Schlei) is a town of very remote origin, and seems to have been a trading place of considerable importance as early as the 9th century.
Charlemagne had established a~ march between the Eider and the Schlei; but in course of time the Danes had not only seized this territory, but had driven the German population beyond the Elbe.
Peace was maintained with Canute, and in 1035 a treaty The was concluded and the land between the Eider and neigh- the Schlei was ceded to Denmark.
The peninsula of Angeln, between the Gulf of Flensburg and the Schlei, is supposed to have been the original seat of the English, and observers profess to see a striking resemblance between this district and the counties of Kent and Surrey.