The Second Schleswig War erupted as a consequence of rising tensions between Denmark and the German Confederation over the control of the duchies of Schleswig and Holstein. The Danish government had sought to consolidate its control over these provinces, which were predominantly inhabited by German speakers. Prussia, seeing an opportunity to exert influence and support the German populace, mobilized its forces and initiated military action. The decision to cross the border into Schleswig marked a significant escalation in the conflict, as it aligned Prussia alongside Austria against Denmark.

The Prussian Army swiftly advanced into Schleswig, applying modern military tactics and organization, which had seen considerable improvements since the previous conflicts in the region. This invasion was strategically timed as the Danish forces were unprepared to face a coordinated attack from two major powers. The combined military pressure from Prussia and Austria was overwhelming, leading to significant territorial gains early in the conflict. The operations of the Prussian forces laid the groundwork for subsequent victories in the war.

The war would eventually lead to a swift Danish defeat and the Treaty of Vienna, which resulted in the transfer of Schleswig and Holstein to Prussia and Austria, respectively. This conflict was pivotal in reshaping the power dynamics in Northern Europe and played a crucial role in the unification of Germany under Prussian leadership. The outcomes set the stage for future conflicts and tensions in the region as the struggle for dominance continued.