The work with gliders in Germany by the Lilienthal brothers, Otto and Gustav (1849-1933), was, arguably, the most important aerial effort prior to that of the Wright brothers, Wilbur and Orville. Otto Lilienthal's numerous flights, over 2,000 in number, demonstrated beyond question that unpowered human flight was possible, and that total control of an aerial device while aloft was within reach.
Lilienthal had a conical hill (about 45 feet high and about 200 feet in diameter) constructed in 1894 near Berlin, Germany, at Gross-Lichterfelde, from which he could glide in any direction. Lilienthal's interest in flight was evident as early as 1861. His work with gliders began in 1891 and continued with various gliders of his own design until 1896.
His abilities as an engineer, mathematician placed him at the forefront of aerial experimentation during the mid-1890's. Otto and his brother Gustav made numerous measurements of lift and drag of various aerofoils during 1874, which they published in 1889. Otto Lilienthal's aerial influence was widespread, and his work was well-known within the U.S. Photographs and engravings depicting Lilienthal in flight were printed in many magazines and journals, and the effect then of seeing a human aloft with great arching wings can hardly be imagined. Even though his total time aloft was rather limited, his 2,000 flights were seen as heralding the coming age of what was then called "Manflight."
Otto Lilienthal's glider collapsed during a flight on August 9, 1896, and he suffered severe injuries. His death, the following day at a hospital in Berlin, was considered a distinct blow to progress in the aerial arts.