The conquest of Benin in 1897 completed the British occupation of southwestern Nigeria. The incident that sparked the expedition was the massacre of a British consul and his party, which was on its way to investigate reports of ritual human sacrifice in the city of Benin. In reprisal a marine detachment promptly stormed the city and destroyed the oba's palace. The reigning oba was sent into exile, and Benin was administered indirectly under the protectorate through a council of chiefs.
...significant events at the turn of this century marked the interior drive by colonialists to gain political and economic control over what later became the central and eastern states of Southern Nigeria... the Benin expedition of 1897...the Benin empire fell in the wake of the so-called "punitive" expedition by Sir Ralph Moor's government on February 18, 1897.
In 1896 a small armed force from the Oil River Protectorate led by the governor entered Bini territory to talk to their ruler about ending slavery and human sacrifice, outside the capital Benin they were ambushed with only two men getting away. Within the month some 1500 men including naval landing parties had been formed to punish the Bini. Despite Bini ambushes on the columns within three weeks they were in the capital Benin along the route of the advance they found the remains of hundreds of men and women sacrificed to the Bini gods. In the capital they found crucified victims and blood stained alters.