The experience of collective subjection under Napoleonic rule awakened a spirit of German nationalism for long dissipated in the dynastic patchwork quilt of the Holy Roman Empire. After liberation, the establishment of a Customs Union (1834) and a common rail network have been described as the ‘Siamese Twins’ facilitating the unification process. However, the Erfurt Union, a notional confederation of the German states under Prussia’s lead was blocked by Austria. When Bismarck became German Chancellor (1862) unification was accelerated with ‘blood and iron’. Prussia’s successful wars against Denmark, and then Austria, particularly its crushing victory over the latter at Sadowa (1866), cemented its German leadership. The North German Confederation, formed to fight Austria, became a de facto polity. The final catalyst for unification would be the comprehensive humiliation of France by Prussia and its German allies (1870–71). Piquantly, the formal creation of the German Empire would take place at Versailles.