An ethnic German from Transylvania, Hermann Julius Oberth came to his spaceflight insights before World War I. In 1923 he published the book "The Rocket into Interplanetary Space." In it he discussed the feasibility of human spaceflight, laid out the basic equations of rocketry, and described how liquid propellants could vastly exceed the performance of gunpowder rockets.
Oberth’s work inspired an explosion of interest in rocketry and space travel in the German-speaking world.
