question: Otto von Bismarck used Lückentheorie while under Prussian leadership in which empire?
answer: German Empire
context: Title: Herbert von Bismarck
  Passage: Nicolaus Heinrich Ferdinand Herbert, Prince von Bismarck (28 December 1849 – 18 September 1904) was a German politician, who served as Foreign Secretary from 1886 to 1890.  His political career was closely tied to that of his father, Otto von Bismarck, and he left office a few days after his father's dismissal.  He succeeded his father as the 2nd Prince of Bismarck in 1898.  He was born in Berlin and died in Friedrichsruh.
  Title: Fürst von Bismarck
  Passage: The great German statesman and diplomat Otto von Bismarck (1815–1898) received several noble titles during the course of his career.  Already born into a noble Junker family, the House of Bismarck, he began life as simply "Mr (German:"Herr") Otto Eduard Leopold von Bismarck".
  Title: Lückentheorie
  Passage: "Lückentheorie" (] , "gap theory") refers to the theory that when the Crown and the Parliament were unable to come to agreement, the Crown could act as it sees fit.  It was in reference to the Constitution of the Kingdom of Prussia, which was established following the revolutions of 1848.  Its political use occurred in 1862 when Otto von Bismarck used it to justify proceeding with taxes for military reforms over the opposition of the Parliament to avoid a constitutional crisis.
  Title: Otto von Bismarck
  Passage: Otto Eduard Leopold, Prince of Bismarck, Duke of Lauenburg (1 April 1815 – 30 July 1898), known as Otto von Bismarck (] ), was a conservative Prussian statesman who dominated German and European affairs from the 1860s until 1890.  In the 1860s, he engineered a series of wars that unified the German states, deliberately excluding Austria, into a powerful German Empire under Prussian leadership.  With that accomplished by 1871, he skillfully used balance of power diplomacy to maintain Germany's position in a Europe which, despite many disputes and war scares, remained at peace.  For historian Eric Hobsbawm, it was Bismarck who "remained undisputed world champion at the game of multilateral diplomatic chess for almost twenty years after 1871, [and] devoted himself exclusively, and successfully, to maintaining peace between the powers".  However, his annexation of Alsace-Lorraine gave new fuel to French nationalism and promoted Germanophobia in France.  This helped set the stage for the First World War.
  Title: Franco-Prussian War
  Passage: 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.
citations: Otto von Bismarck Lückentheorie