The restoration of the world order following the Napoleonic Wars indeed brought a relatively peaceful era to Europe for some thirty years. Disdain for the authoritarian monarchies and empires began to grow during the 1840s and the first elements of modern nationalism and socialism began to emerge. In 1848 Europe erupted into a series of revolts that affected nearly every nation except Great Britain. France’s monarchy ended abruptly and riots in Germany, notably Baden, Hessen Kassel and Berlin brought swift and violent responses. The Danish Duchies of Schleswig and Holstein attempted to secede, but were defeated by the Danes in a six month war despite the interjection of Prussia. It was, however in the Austrian Empire that the disturbances became full blown wars. Although the revolt of the Czechs in Prague was brutally put down, the uprisings in Italy and Hungary tested the Hapsburg regime the most. The Hungarian revolution was crushed by General Hanau with help from a Russian Army within a year and the Italians were also decisively defeated by Field Marshall Radetzky in March of 1849 at the Battle of Novara.

The Hapsburg Empire, which came very close to collapse during these times now took steps to gain hegemony of the entire German speaking central Europe. The most resistance to this came from Prussia, the largest entity in the German Confederation whose parliament was at Frankfurt-am-Main. Prussia offered a solution that would make them dominant but they were out-manoeuvred by the Austrians by the Treaty of Olmütz (dubbed a “Humiliation” by Prussia) and relations between the two became strained.
In 1862, Otto von Bismarck was appointed Minister President of Prussia by King Wilhelm I. The conservative Bismarck’s agenda was the unification of the non-Austrian German States and by that virtue, the exclusion of Austria from German affairs. Bismarck, who has been judged as one of the most brilliant politicians of the 19th century, saw his chance with the re-emerging problem of the Danish Duchies of Schleswig and Holstein which he had determined that Prussia would annex. The Danish King, by constitution, declared the Duchies would remain part of his kingdom. The Confederation sent troops to occupy the Duchies and Prussia and Austria, following the Convention of Gastein, demanded the Danes retract the declaration. Upon the negative reaction, both nations sent troops across the border. 
The Second Schleswig War as it was known began in early February 1864 and began with actions at Missünde by the Prussians and Oeversee by the Austrians. By mid-March the Danes had retreated to the Fortress of Düppel where a siege began. The fortress fell at the end of April and after a seaborne landing at Alsen, the Danes sued for peace.

Bismarck now manoeuvred to make good on his desire to annex the Duchies for Prussia. Both countries developed a contentious debate over the administration of the Duchies with Bismarck constantly criticizing the Austrians for their part. Undoubtedly the Austrians were provoked to make military moves that allowed Prussia to claim an offensive intent. The members of the confederation began to take sides early in 1866. Hanover, Saxony, Bavaria, Baden and Württemberg sided with Austria along with Nassau and the Hessian Grand Duchies. The bulk of the North German States such as Mecklenburg, Oldenburg Lippe-Detmold, Anhalt, Waldeck, The Hanseatic Cities and most of the Thuringian Duchies were with Prussia.
By the middle of May 1866, Bismarck had convinced King William I that war was the only solution. On the 8th June, Prussian troops entered Holstein, forcing Austria to withdraw their troops. The Frankfurt parliament voted for all parties to halt warlike preparations but Prussia was intent on breaking up the confederation and enforcing the proposals for Prussian supremacy put forward in 1849. On 15th June Ultimatums were presented to Hanover and Electoral Hesse for them to demobilize and upon rejection the Prussians marched into them on 19th June. By this time Prussian armies were moving to the Saxon border which they crossed on the 18th (The Saxon Army had left to join their Austrian before the Prussians arrived) and crossed the Austrian border in Bohemia on the 22nd. The Seven Weeks War had begun.

HOW PRUSSIA AND AUSTRIA CAME TO WAR IN 1866
TO BE CONTINUED