What happened
On the death of President Paul von Hindenburg, Hitler merged the presidency with the chancellorship and took the title of Fuhrer, while the military oath was redirected personally to him.
Why it matters
This is the endpoint of Hitler's rise within Germany. It marks the conversion of political leadership into personal dictatorship and the disappearance of the last formal separation between regime offices that might have limited him.
Notes
Use this as the terminal event for the Nazi-rise timeline.