Otto von Bismarck used Lückentheorie while under Prussian leadership in which empire?
Lückentheorie:  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. Otto von Bismarck:  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.
German Empire