The German Federal Army (German: "Deutsches Bundesheer" ) was the military arm of the German Confederation from 1815 to 1866 whose purpose was the defence of the Confederation against external enemies - primarily France, from where several wars of occupation had been launched in earlier times against the Holy Roman Empire, but also Russia and its attempts at expansion in the cause of Pan-Slavism.
 Cases of conflict between the federal allies, such as arose later during the Second Schleswig War  (the Duke of Holstein was simultaneously the King of Kingdom of Denmark), were not anticipated or governed.
 The Austro-Prussian War, provoked by Kingdom of Prussia against the Austrian Empire, for domination of the German Confederation and its allies led to the defeat of the Federal Army in 1866 and thus to its disbandment.
After the dissolution of the Holy Roman Empire by Napoleon in 1806, the German-speaking remnants of the empire became organized into a conglomerate of independent kingdoms, duchies, principalities and city-states.
 This article lists the member states of the German Confederation of 1815–1866, the North German Confederation of 1867–1871, the German Empire of 1871–1918, and the Weimar Republic of 1919–1933.
The North German Confederation (German: "Norddeutscher Bund" ) was the German federal state which existed from July 1867 to December 1870.
 Some historians also use the name for the alliance of 22 German states formed on 18 August 1866 ("Augustbündnis ").
 In 1870–1871, the south German states of Baden, Hesse-Darmstadt, Württemberg and Bavaria joined the country.
 On 1 January 1871, the country received a new constitution that gave it the name "German Empire" but largely remained the same, which is why the North German Confederation continues as the German nation state which still exists today.
The Austro-Prussian War or Seven Weeks' War (also known as the Unification War, Prussian–German War, German Civil War, War of 1866, Brothers War, or Fraternal War, and in Germany as the German War) was a war fought in 1866 between the German Confederation under the leadership of the Austrian Empire and its German allies on one side and the Kingdom of Prussia with its German allies on the other, that resulted in Prussian dominance over the German states.
 Prussia had also allied with the Kingdom of Italy, linking this conflict to the Third Independence War of Italian unification.
The Battle of Hühnerwasser was the first battle of the Austro-Prussian War.
 It was the first engagement in the opening days of the Königgrätz campaign, fought in Bohemia on 26 June 1866.
 It was fought between troops of the Prussian Elbe army and troops from the Austrian I Corps, led by Leopold Gondrecourt.
The conference of the six Great Powers (which for the first time included Italy) which met at London in May, 1867, to settle the political order of northern Europe after the disruption of the German Confederation in 1866 is known as the London Conference of 1867.
 It resulted in the Treaty of London of May 11, 1867.
 The immediate occasion of the conference was the necessity of settling the status of the Grand Duchy of Luxemburg, which, after the downfall of the First Napoleon, had been added to the dominions of the King of the Netherlands as a separate and independent state and made a member of the German Confederation.
 Notwithstanding the dissolution of the confederation, Luxemburg continued to be occupied by Prussian troops, the French government insisting upon the removal of these troops and threatening war to enforce the demand.
The Franco-Prussian War or Franco-German War (German: "Deutsch-Französischer Krieg" , French: "Guerre franco-allemande" ), often referred to in France as the War of 1870 (19 July 1870 – 10 May 1871), was a conflict between the Second French Empire of Napoleon III and the German states of the North German Confederation led by the Kingdom of Prussia.
 The conflict was caused by Prussian ambitions to extend German unification and French fears of the shift in the European balance of power that would result if the Prussians succeeded.
 Some historians argue that the Prussian chancellor Otto von Bismarck deliberately provoked a French attack in order to draw the independent southern German states—Baden, Württemberg, Bavaria and Hesse-Darmstadt—into an alliance with the North German Confederation dominated by Prussia, while others contend that Bismarck did not plan anything and merely exploited the circumstances as they unfolded.
Charles Augustus Zollinger (December 9, 1838 in Wiesbaden, German Confederation - December 27, 1893) was an American Civil War hero on the Union side, and later served six terms as Mayor of Fort Wayne, Indiana.
 As a Colonel in the US Army, he led troops into battle at Murfreesboro, Shiloh, Franklin and Nashville.
 Born in Wiesbaden in the German Confederation to German parents of Swiss heritage, he emigrated along with his family in 1848, arriving in New York before settling in Sandusky, Ohio and soon after moving to Marion, near Fort Wayne, Indiana.
The states of the German Confederation were those member states that from 20 June 1815 were part of the German Confederation, which lasted, with some changes in the member states, until 24 August 1866, under the presidency of the Austrian imperial House of Habsburg, which was represented by an Austrian presidential envoy to the Federal diet in Frankfurt.
The North German Confederation Treaty (in German "Augustbündnis", or Alliance of August) (also called the North German Federation Treaty and the Treaty of 18 August 1866) was the treaty between the Kingdom of Prussia and other northern and central German states that initially created the North German Confederation, which was the forerunner to the German Empire.
 This treaty, and others that followed in September and October, are often described as the "August treaties", although not all of them were concluded in August 1866.

Question: Which war ought in 1866 between the German Confederation was the Battle of Hühnerwasser  the first battle of 
Answer: The Austro-Prussian War