The experience thus obtained led to his being selected to command an expedition. sent by the Royal Geographical Society in 1873, to assist Dr Livingstone. He was also instructed to make independent explorations, guided by Livingstone's advice. Soon after the departure of the expedition from Zanzibar, Livingstone's servants were met bearing the dead body of their master. Cameron's two European companions turned back, but he continued his march and reached Ujiji, on Lake Tanganyika, in February 1874, where he found and sent to England Livingstone's papers.
Cameron spent some time determining the true form of the south part of the lake, and solved the question of its outlet by the discovery of the Lukuga river. From Tanganyika he struck westward to Nyangwe, the Arab town on the Lualaba previously visited by Livingstone. This river Cameron rightly believed to be the main stream of the Congo, and he endeavoured to procure canoes to follow it down. In this he was unsuccessful, owing to his refusal to countenance slavery, and he therefore turned south-west. After tracing the Congo-Zambezi watershed for hundreds of miles he reached Bihe and finally arrived at the coast on November 28, 1875, being the first European to cross equatorial Africa from sea to sea.
His travels, which were published in 1877 under the title Across Africa, contain valuable suggestions for the opening up of the continent, including the utilization of the great lakes as a Cape to Cairo connection. In recognition of his work he was promoted to the rank of Commander.
The remainder of Cameron's life was chiefly devoted to projects for the commercial development of Africa, and to editing and writing. His last work was the editing of the personal adventure narrative of the Master Mariner James Choyce, who had sailed as a teenager in 1797 aboard a whaler to the Pacific Ocean. Choyce's narrative covering 26 years of seafaring life is one of the earliest works of an Englishman's experiences in South America.
Cameron visited the Euphrates valley in 1878-1879 in connection with a proposed railway to the Persian Gulf, and accompanied Sir Richard Burton in his West African journey of 1882. At the Gold Coast Cameron surveyed the Tarkwa region, and he was joint author with Burton of To the Gold Coast for Gold (1883).
He was killed, near Leighton Buzzard, by a fall from horseback when returning from hunting in 1894.
A second edition of Across Africa, with new matter and corrected maps, appeared in 1885. A summary of Cameron's great journey, from his own pen, appears in Dr Robert Brown's The Story of Africa, vol. II, pp. 266-279 (London, 1893).
Across Africa was republished in 2005.
V.E. Cameron "Across Africa", ISBN 1-904466-26-5.
R.F. Burton, V.E. Cameron "To the Gold Coast for Gold", ISBN 1-4142-4575-0.
James Choyce "Log of a Jack Tar: James Choyce, Master Mariner", ISBN 0-7041-0005-3