Economic success, political failure, and diplomatic tension marked the idea of a unified Germany in the period after the Napoleonic Wars. Prussian merchants, with the support of the Prussian crown, established the customs and trade union known as the Zollverein in 1834. The Zollverein freed trade between most of the German states, with the exception of Austria. Industrialists and merchants thus brought liberal politics into German nationalism. During the Revolution of 1848, liberals met in the Frankfurt Assembly and drafted a constitution modeled on the ideals of the French Revolution of 1789. The assembly offered to share power under a constitutional monarchy and offered the crown of a unified Germany to Frederick William IV of Prussia. The Revolution of 1848 brought some liberal reforms to Prussia, such as the ability of the parliament to obstruct certain forms of taxation. However, the Prussian leadership, which was thoroughly conservative, rejected the Frankfurt constitution, preferring reform and unification directed from above. Austria's resistance to attempts to unify Germany under Prussian leadership further obstructed unification. One of the major questions concerning German unification centered on this Prussian-Austrian rivalry, which was both diplomatic and cultural. Supporters of