The man who did most to unite the German states was Otto Von Bismarck. He was the Prussian Chancellor and his main goal was to strengthen even further the position of Prussia in Europe. His primary aims were to:
unify the north German states under Prussian control
weaken Prussia's main rival, Austria, by removing it from the Bund
make Berlin the centre of German affairs - not Vienna
strengthen the position of the King of Prussia, William I, to counter the demands for reform from the Liberals in the Prussian parliament (the Reichstag).
It is important to note that there is much debate about Bismarck's aims to unify all German states under Prussian rule. Some historians argue that Bismarck only intended to unify the north German states but the strength of nationalist feelings after 1866 led to German unification under its own steam. According to this opinion, Bismarck actually reacted to political changes in other German states and capitalised on it rather than pursuing a master plan from the beginning to control all German states.
Army reforms
Bismarck wanted to build up Prussia's army in case his unification plans led to war. To do this he needed money. The Prussian parliament refused to allow money to be raised for Bismarck's military reforms.
Bismarck ignored the Reichstag and simply collected the money for army reforms through general taxation. He never bothered to obtain permission from the Reichstag.
Congress of Princes 1863
To counter Prussia's growing influence, Austria tried to strengthen its position in the Bund. Since it was in theory the leading member of the Bund, an increase in the power of the Bund would strengthen Austria.
Bismarck thwarted Austria's plans by insisting on popular elections to the Diet (the Bund's parliament). Austria refused and neither its or Bismarck's reforms happened.
Bismarck had successfully ruined Austria's plans and was seen, ironically, as a defender of the Liberal nationalists.
