Prussia and Austria agreed at Bad Gastein on how to administer Schleswig and Holstein, territories taken from Denmark in 1864. The deal postponed a larger struggle over leadership in Germany but did not resolve the underlying rivalry. That rivalry soon pushed the German states toward new military alignments.
After fighting against Prussia in 1866, Württemberg concluded a Schutz- und Trutzbündnis (protective and defensive alliance) with Prussia. Such agreements typically meant coordinated defense planning and acceptance of Prussian leadership in wartime. This was an early step linking southern German armies to Prussia without formal political unification.
Baden concluded a similar protective alliance with Prussia, tying Baden’s military planning to Prussian strategy. The agreement reinforced Baden’s shift away from the former German Confederation system toward direct cooperation with Prussia. It also set the stage for Baden’s later, deeper military integration.
Bavaria made peace with Prussia after the 1866 war and accepted terms that included indemnities and limited territorial changes. At the same time, Bavaria entered a protective relationship with Prussia, even while staying outside Prussia’s new northern federation. The arrangement balanced Bavarian autonomy with Prussian-led security cooperation.
Prussia and Austria signed the Peace of Prague, ending the 1866 war and reshaping German politics. Austria accepted exclusion from German affairs and the old German Confederation was effectively ended. With the previous federal defense framework gone, southern German states had to rethink how they would provide for their security.
Hesse-Darmstadt signed a peace treaty with Prussia after the 1866 war. The treaty required reparations, territorial adjustments, and a loss of some independent powers. It also pushed Hesse’s northern territories toward membership in Prussia’s emerging northern political-military system.
The 1866 protective alliances with Bavaria, Württemberg, and Baden were initially kept secret. Their publication signaled that Prussia had extended a military leadership role beyond the Main River line in practice, even before formal political union. Public knowledge of these ties also affected debate inside the southern states about sovereignty and security.
Prussia and Hesse concluded a protective alliance that was not kept secret in the same way as the 1866 agreements. This strengthened Prussia’s influence over Hessian defense arrangements at a time when Germany’s old federal military system no longer existed. Together with other southern alliances, it tightened the North–South security link.
Prussia led the formation of the North German Confederation, a new federation of northern German states. It created shared institutions and placed military command in Prussian hands, building a stronger unit than the former German Confederation. The southern states remained outside, but their earlier protective treaties meant they were already tied to Prussia in defense planning.
War with France made the security logic of the Prussia–southern state agreements immediate and practical. The southern German states fought alongside Prussia, demonstrating that treaty-based cooperation could function as a working coalition in a major conflict. This wartime partnership helped create political momentum for formal union.
During the war, Baden and Hesse agreed with the North German Confederation on terms for joining a wider German federal structure. This treaty provided the constitutional bridge from wartime cooperation to political unification. It also prepared the way for new, clearer rules about how the southern armies would relate to the federal army system.
Bavaria agreed to join the expanded federal union but negotiated important “reserve rights,” including special arrangements affecting its army in peacetime. This was a compromise: Bavaria accepted unification while retaining distinctive institutions and a measure of military autonomy. The deal reduced the risk that Bavaria would oppose unification outright.
Baden concluded a military convention regulating how its troops would relate to the Prussian-led federal army. Unlike “reserve-right” models, Baden’s convention is often described as an integration type, bringing a formerly independent army into the Prussian army structure. This made wartime cooperation permanent and administrative, not just political.
Württemberg agreed to accession terms and, at the same time, concluded military arrangements with the North German Confederation. Like Bavaria, Württemberg retained more limited military distinctiveness than states whose forces were fully merged into Prussian structures. This completed the main set of southern accessions needed for a unified German federal state.
After the November treaties took effect, the German Empire was proclaimed at Versailles. The earlier protective alliances and later military conventions helped make unification workable by aligning armies under a common command system while allowing some negotiated exceptions. The result was a new federal empire with Prussia at its center and a shared framework for military organization and wartime command.
Military conventions and treaties between Prussia and the southern German states (1866–1871)