From the records of the Colonial Office and from the dead man 's diary we learn that a certain young English nobleman , whom we shall call John Clayton , Lord Greystoke , was commissioned commission to make a peculiarly delicate investigation of conditions in a British West Coast African Colony from whose simple native inhabitants another European power was known to be recruiting soldiers for its native army , which it used solely for the forcible collection of rubber and ivory from the savage tribes along the Congo and the Aruwimi .