The expedition to find the source of the Nile River was led by British explorer Henry Morton Stanley in the 19th century. Commissioned by the New York Herald newspaper, Stanley set out in 1869 and embarked on a challenging journey through the uncharted territories of Africa. He famously traced the Congo River but eventually made notable contributions to the understanding of the Nile's geography. His explorations highlighted the potential for exploitation and colonization in Africa, with the Nile serving as a vital water source for surrounding nations and influencing European interests in the continent.