Hitler became Chancellor of Germany in late January of 1933, appointed by the conservative President von Hindenberg in an attempt to ensure the Socialist Democratic Party (SPD) would not regain power. Soon after, the Nazis unleashed a widespread campaign against its primary rivals, the SPD and Communist parties, focusing largely on the Iron Front and Antifa, the more militant paramilitary portions of each party respectively. This was done under the auspices of ending the street violence which had wracked Germany for over a year, violence that the Nazis had been a primary player in causing. Hindenburg greatly disliked both the SPD and Communists, so turned a blind eye to these activities. Hitler further ingratiated himself to Hindenburg by promising that his ultimate goal was to re-establish the monarchy, the long-term goal of the ailing president. To support this, Hindenburg agreed to hold another round of elections in March in order to allow the Nazis to consolidate their power.
Prior to the elections occurring, the German parliament building, known as the Reichstag, was burnt to the ground by arsonists. Though evidence existed that the Nazis themselves set the fire, they blamed Communist provocateurs and used it as proof of a Communist plot to overthrow the government. Hindenburg, who by this time was an increasingly confused old man, agreed to an emergency decree which greatly curtailed civil rights and centralized power to the Chancellor in the name of security. With this new decree in hand, Hitler and his Nazis completely dismantled the German Communist party, arresting its leaders and banning its meetings. Members of the SPD were also threatened and assaulted, and Nazi party members monitored all voting sights. However, despite these moves, Hitler still only managed to win 43% of the vote in the March election, with the SPD and Communists maintaining their role as the second and third largest parties.
Hitler’s failure to obtain his desired majority did not stop him for long. Instead, with Hindenburg’s blessing, he pushed forward with passing what became known as the Enabling Act, a piece of legislation that effectively gutted the country’s constitution and gave Hitler broad dictatorial powers for a period of four years. Hitler needed a two-thirds majority to pass the Enabling Act, which he achieved by targeting what was left of the remaining small conservative parties, threatening them with violence and arrest if they didn’t vote his way, with Nazi paramilitaries literally watching over their shoulders. With the Communists unable to seat their members, because most were in prison or had fled, only the SPD voted against it. The measure passed in late March of 1933.
When Germany’s parliament effectively sidelined, the only threat to Hitler’s power was the ailing Hindenburg, who retained the ability to remove Hitler as Chancellor. Hitler did not dare directly challenge Hindenburg due to the old man having the unwavering support of the military. Instead, Hitler focused on leaving Hindenburg no other options, declaring the SPD illegal and convincing the remaining conservative parties to dissolve by mid-summer. He also gained popular support by pouring money into new programs and public works projects and gained the support of the armed forces by promising to rebuild their strength. The national government took full control of all aspects of governing the country, and Jews were ejected from the civil service and universities.
At first, Hindenburg only spoke up once during all of this, demanding that Jewish veterans be allowed to keep their positions. However, as the Nazis seized more power and their paramilitary units became more out of control, he steadily became more alarmed. Eventually, in the summer of 1934, Hindenburg demanded that Hitler either get the paramilitaries under control, or face being removed in favor of martial law under the military. Hitler responded by having the leaders of the old Nazi paramilitaries, many of them hardcore socialists who had been involved in most of the street fighting in the early years, killed. This mollified Hindenburg and allowed Hitler to replace the paramilitaries with a more disciplined secret police under his more direct control. This was also done to further gain the support of the military. When Hindenburg died in August, they backed Hitler as his successor as president.
The death of Hindenburg ended that last illusions of the old German republic. Over the next year the line between the state and the Nazi party was completely wiped away and the two became fused together. The party took complete control over all aspects of German society and culture. Nazi ideology became German ideology. Jews and other groups labeled as unwanted by the state were stripped of their citizenship, forced into ghettos, and eventually shipped to extermination camps. The German military rearmed itself in preparation for the coming conflict. As they say, the rest is history.