Haderslev County is a former province in Denmark, located on the northernmost part of Southern Jutland. Haderslev County was established in 1920 following the reunification of Denmark and South Jutland following the Schleswig Plebiscites. It was dissolved in 1970 when it merged with three other counties to form South Jutland County. Haderslev County corresponded geographically to the former Prussian Kreis Hadersleben except for Hvidding Herred which was transferred to Tønder County. Half of Tyrstrup Herred was transferred from Haderslev County to Vejle County when Denmark surrendered Schleswig to Prussia and the Austrian Empire in 1864, and this region remained Danish.