Otto was born in the village of Holzhausen, near Frankfurt. His father, an innkeeper, died when Otto was a small boy. This was a period of declining prosperity in Germany, although Otto's mother had hoped her son might receive a technical education, Otto was forced to leave school and take up employment in a Frankfurt grocery store. His brother Wilhelm, who had a textile business in Cologne, then secured him a position as a salesman in tea, sugar, and kitchen ware to grocery stores. Otto's travels took him along the German border with France and Belgium as far as Cologne where in 1859 he met Anna Gossi and began a nine-year courtship.

In 1860 Jean Lenoir built the world's first mass production internal combustion engine, a noncompression double-acting gas engine. Otto saw the potential of the Lenoir engine and perceived that the future development...