Who was the first diesel engine?

The first diesel engine was invented by Rudolf Diesel, a German engineer, in 1897. Diesel designed the engine to be more efficient than existing steam engines, aiming to utilize the energy from fuel more effectively. His prototype was a single-cylinder, four-stroke engine that ran on peanut oil, demonstrating the potential for using various fuels. Diesel's invention laid the foundation for modern diesel technology used in transportation and industry today.