January 31, 1917: Kaiser Wilhelm II signs the order to begin unrestricted submarine warfare.

It is no coincidence that the United States entered the war within months of this announcement - German U-boats had been a point of dispute between the two countries before “unrestricted warfare” even began. Knowing (or perhaps hoping) that America would be unwilling to declare war, a desperate Germany finally moved to try to thwart the Britain’s damaging blockade with their own (less effective) policy - unrestricted submarine warfare. 

The Kaiser responded enthusiastically to this proposal, which was also supported by most of the German military leaders and the main parties in the Reichstag. President Wilson, however, already a critic of the despotic Wilhelm, broke off diplomatic relations with Germany - this, ultimately, was not enough. After the sinking of several American ships by German U-boats, Wilson was moved to urge Congress declare war, and on April 6th, 1917, the United States entered World War I. The second of Wilson’s fourteen points was, in fact, “freedom of the seas”.  

January 30, 1933: Adolf Hitler is sworn in as Chancellor of Germany.

This event, sometimes referred to as Machtergreifung (“seizure of power”), is commonly regarded as the beginning of the Third Reich. The NSDAP had been slowly growing in popularity over the previous few years, and by 1931, they had become the largest party in the Reichstag. As anti-Nazi Germans shrank back and continued their failure to organize against the growing party, Hitler seized his chance and was appointed Chancellor of a coalition government made up of the NSDAP and DNVP (a nationalist party similar to the NSDAP).

Although at this time Hitler was still technically bound by the constitution and the power of the other parties (who, combined, still outnumbered the NSDAP-DNVP coalition), he immediately set forth to eliminating other parties and consolidating power over the next four years. This was a period known as Gleischaltung - the period during which the Reichstag Fire Decree (the suspension of civil liberties) and the Enabling Act (the allocation of legislative power into the hands of Nazi leaders) were both passed; the period during which the NSDAP became the country’s only legal party; the period during which Hitler’s blood purge of the SA was carried out.

Within four years, the Weimar Republic had become Nazi Germany.