In 1856, John Hanning Speke was sent by the British Royal Geographical Society to discover lakes believed to exist in eastern Africa. In 1858, Speke and fellow explorer Sir Richard Francis Burton discovered Lake Tanganyika. Speke and Burton split, and while traveling on his own, Speke discovered Lake Victoria and claimed it to be the source of the Nile River. Though many did not believe the lake was the source, Speke returned to the lake in 1860 and proved Lake Victoria was indeed the source of the Nile River.