Barnack was an engineer working for the German camera manufacturer, Leitz, and he was inspired to create a small, portable camera that could take high-quality photographs. The Ur-Leica was the result of his efforts, and it was the first camera to use 35mm film. This was a major breakthrough, as it allowed photographers to take many more pictures than was possible with the larger format cameras of the time.
The Ur-Leica went through several iterations before it was commercially released in 1925 as the Leica I. It quickly became popular among photographers, and its compact size and high-quality images made it a favorite of photojournalists and street photographers. The Leica brand went on to become one of the most famous and respected camera brands in the world, and its influence can still be seen in modern digital cameras today.