The longest one word title was written by this general?

The longest one-word title in history is attributed to Generalissimo Francisco Franco, the dictator of Spain from 1939 to 1975.

His official title was "Caudillo de España", which translates to "Leader of Spain." It's not a single word in English, but in Spanish, "Caudillo" is a single word, making it the longest one-word title in history.