How did Otto von Bismarck become prime minister of Prussia?

Otto von Bismarck became the prime minister of Prussia in September 1862 during a period of intense political crisis.1

For over two years, King William I had been locked in a struggle with the liberal majority in the Chamber of Deputies over proposed military reforms, specifically regarding the size of the military and the length of service. When the liberal majority refused to approve the necessary revenue, the King refused to compromise on his sovereign authority over the military.12

Facing a stalemate and contemplating abdication, William I was dissuaded by his advisors and instead appointed Bismarck as a "last desperate effort" to avoid parliamentary sovereignty over the military. Bismarck, who had previously served as an ambassador to Russia and France, was brought in to break the deadlock. He subsequently bypassed the legislature by declaring a "gap" in the constitution, allowing the government to collect and spend taxes without parliamentary approval to implement the military reforms.12