Here's a brief timeline:
* 1860s: Étienne Lenoir developed the first commercially successful internal combustion engine, which was a two-stroke design.
* 1876: Nikolaus Otto patented the first successful four-stroke engine, which was more efficient than Lenoir's two-stroke design.
While the four-stroke engine ultimately became more popular due to its efficiency, the two-stroke engine predates it and was crucial in the development of the internal combustion engine.
