Planck had always been a nationalist and vocal champion of Germany's cause, he also elected to stay out of politics as much as possible. After World War I, Planck became a member of the Deutsche Volkspartei, the German People's Party. This moderately conservative group advocated the unification of the German people and pushed for Germany to regain its position in the world. But politics was far from the top of Planck's agenda, and he disliked concerning himself with political issues. But there was no way he would be able to avoid the political issues lurking on Germany's horizon.
In the early 1930s, nothing was going well: there was an economic depression, the increasingly powerful political extremists drowned out the voice of more moderate political parties, and anti-Semitism pervaded government and academic life. Things were bad for Germany, but they were about to get much, much worse.
On January 30, 1933, Adolf Hitler became Chancellor of the German Reich.
Planck expected that once in a national office, Hitler would have to become more moderate in order to hold into his power. But the chancellor soon proved himself even more extreme than anyone had realized. His attacks on the German Jews took a speedy toll on German science. On April 7, 1933, the German government passed the Law to Restore the Career Civil Service. The law defined a non-Aryan as anyone with a non-Aryan parent or grandparent, and anyone fitting this broad definition was no longer allowed to hold a civil service job. In most cases, non-Aryan meant Jew, and the law spelled the beginning of the end for German Jewish scientists, many of whom immediately began preparing to leave the country.
The law resulted in the firing of over one thousand university teachers. Since there tended to be more Jewish theoretical physicists than applied physicists, theoretical physics programs suffered heavily from the dismissal of professors. Before 1933, there were about sixty teachers at German universities working in theoretical physics; after April of 1933, twenty-six of these left their positions. The departed academics included six Nobel laureates and eight who would go on to later win the Nobel Prize. An American scientist visiting Germany at the time observed that "[m]ost people don't give a darn; a large proportion is rather glad it all happened."
This was only the beginning. As Hitler's campaign against the Jews expanded, Germany lost twenty-five percent of its theoretical physicists, either by government-imposed dismissal or voluntary exodus. The best and the brightest of Germany's physicists left their jobs and left the country, including Edward Teller, Victor Weisskopf, Hans Bethe, and Max Born.