The Second Schleswig War took place from 1864 to 1865, primarily between the Kingdom of Denmark and the allied forces of Prussia and Austria. The conflict arose over the control of the duchies of Schleswig and Holstein, which had significant German populations. The war ended with a decisive victory for the Prussian-Austrian alliance, leading to the Treaty of Vienna. As a result of the war, Denmark ceded both duchies to Prussia and Austria. This conflict was significant in the context of German unification, as it set the stage for future tensions between Prussia and Austria, ultimately leading to the Austro-Prussian War in 1866.