Because Hitler and his Nazi Party rose to power in the final years of the Weimar Republic the era has been seen as one of failure. But the history of Weimar, Germany's republican government from the end of World War 1 to 1933, is far more complicated and also crucial to understanding how Hitler came to power.

The Creation of the Weimar Republic

Germany entered into World War 1 as an autocracy under Kaiser Wilhelm II, a man who didn't have to pay much attention to requests from his neutered parliament.

However, as the war dragged on and as living conditions in Germany worsened, with food and fuel shortages as well as inflation, public opinion began to turn against the Kaiser. In 1918, with the German war effort failing, the now military government looked at the internal ferment in Germany and concluded the nation was ready to rise in rebellion. Eric Ludendorff, the war leader who had taken practical control of the nation from the Kaiser, tried to create a constitutional monarchy led by a reigned in Kaiser both to help Germany survive and to take the blame for the surrender from the military.
This was too little too late for a German populace shocked by the conclusion to the war, and across the nation people rose in revolution; at this point the demands were closely identified with socialism. Soon the Kaiser had fled to Holland and a coalition government of left wingers was created under Ebert to prepare a new constitution for Germany. Ebert was a pragmatist who began to guide the government down a path of reconciliation, avoiding the more dedicated socialist reforms some were demanding, although he lost left wing support by doing so.

There was street fighting between left and right.

Ebert's government was able to hold elections, and a National Constituent Assembly was voted into being. However, due to disturbances continuing in Berlin - the city had recently contained the Spartacist uprising - the Assembly met at a nearby town: Weimar.

More on the German Revolution of 1918 - 19.

Weimar's Constitution

As the Constituent Assembly sat a team drew up a new constitution for the German Republic. This was finished and voted as approved by a heavy majority on July 31st. It was an interesting mix of ideas taken from elsewhere in the world, and parts of previous German states. While the term Reich was allowed to remain, the state was to be a republic and a democracy, built around a federal structure of 17 sub-states.
It was headed up by a president elected every seven years, who controlled the army, could force laws through by using a decree, could dissolve parliament, and appoint the Chancellor. In practice the president was expected to choose the head of the largest party in the parliament as Chancellor, but this mixture of strong powers meant the President wasn't under parliamentary control. The parliament itself has two houses: the Reichstag, the largest, was elected every four years via proportional representation and the smaller Reichsrat, filled with representatives from the federal states. Weimar had a Bill of Rights which enshrined a number of key human rights, such as free speech, equal treatment from the law, welfare, liberty and religious freedom. There was to be no state approved churches.

However, alongside much of the new was a continuation of the old. The military retained a strong Prussian and landowning bias among the officer core, while the civil service bore the result of several decades of imperial practice. The legal system looked fair, but many of the judges were holdovers from the past and favoured right wings causes. Weimar had this been built by a left wing coalition, but it left a lot of right wing, or at least conservative, power in place, which would exert an ever greater pull on the nation. Much about Weimar has been blamed for allowing or causing the rise of the Nazis, and the constitution has taken some of the blame: proportional representative for allowing splinter groups and minority extremists to gain power, the great power the president could wield for allowing Hitler a chance to remould Germany, and the retention of conservative power structures for weakening the revolution.

The Treaty of Versailles

In 1919 the time bomb Ludendorff had left began to tick. Many Germans had hoped for an equitable peace by conceding defeat in World War One, but what they were given was the Treaty of Versailles, with war guilt clauses, destruction of their army and huge territorial losses. This outraged a Germany which thought Woodrow Wilson's Fourteen Points would have allowed a compromise. But Germany was in no position to reject the treaty, and certainly could not go to war again yet, and after the first Weimar government resigned in protest, a new one signed the peace. The Treaty soon became known to the Germans as the Diktat, the dictated piece, and it was hated widely in Germany for its perceived unfairness and the humiliation, attributes historians have continued to identify.
Weimar faced having to pay back huge reparations which adversely affected the recovering economy, and the role they played in Weimar's economic struggles, while perhaps overplayed at one point, is still discussed and significant. Furthermore, the Treaty has often been blamed as a key factor in the start of World War 2. While this is now downplayed by historiography, the Treaty did have a major effect on the new republic. It wasn't so much that Weimar was weakened by the losses of land, economic power and money, but the way the civilian, republican government had to sign the armistice, the treaty and take the blame, exactly as Ludendorff had wanted, and so they became associated with Germany's disgrace. This allowed the right wing, including the Nazi Party, to paint Weimar's government as traitors and cowards - as 'November Criminals' - who had stabbed true Germans in the back. It was an entirely inaccurate view, a pernicious one, and easy to use in propaganda.