In 1912 Hess found that the rate of production of ions in the atmosphere grows with altitude. In 1933 Regener observed a maximum rate of production above 20 km, a result later confirmed with his student, Pfotzer (Nature 1935). Final results were published in German by Pfotzer alone, probably because Regener had difficulties with the National Socialist government, and the maximum has become known as the Pfotzer maximum. An argument is made for renaming the maximum the Regener--Pfotzer maximum.