In 1857, British explorers Richard Burton and John Hanning Speke led an expedition from Zanzibar to find the source of the Nile River. Despite personal differences, they became the first Europeans to reach Lake Tanganyika in 1858. During the return journey, Speke left Burton and discovered Lake Victoria, which he identified as the Nile's source.

Speke's claim was met with skepticism from Burton. In 1860, Speke and James Grant mapped part of Lake Victoria and found the Nile's exit, the Ripon Falls. On the eve of a public debate with Burton, Speke died in a hunting accident in 1864. Speke's discoveries were later confirmed, and he is credited as the first European to reach Lake Victoria and identify it as the Nile's source.