power. The Ogboni was a very powerful secret society composed of aristocratic freemen noted for their age, wisdom and importance in religious and political affairs. Its members enjoyed immense power over the common people due to their religious station. A testament to how widespread the institution was is the fact that there were (and still are) Ogboni councils at nearly all sub-courts within Yorubaland. Aside from their duties in respect to the worship of the earth, they were responsible for judging any case dealing with the spilling of blood. The leader of the Ogboni, the Oluwo, had the unqualified right of direct access to the Alaafin of Oyo on any matter. Military There was a high degree of professionalism in the army of the Oyo Empire. Its military success was due in large part to its cavalry as well as the leadership and courage of Oyo officers and warriors. Because its main geographic focus was north of the forest, Oyo enjoyed easier farming and thus a steady growth in population. This contributed to Oyo's ability to consistently field a large force. There was also an entrenched military culture in Oyo where victory was obligatory and defeat carried the duty of committing suicide. This do-or-die policy no doubt contributed to the military aggressiveness of Oyo's generals. Cavalry The Oyo Empire was the only Yoruba state to adopt cavalry; it did so because most of its territory was in the northern savannah. The origin of the cavalry is unclear; however, the Nupe, Borgu and Hausa in neighbouring territories also used cavalry and may have had the same historical source. Oyo was able to purchase horses from the north and maintain them in metropolitan Oyo because of partial freedom from the tsetse fly. Cavalry was the long arm of the Oyo Empire. Late 16th and 17th century expeditions were composed entirely of cavalry. There were drawbacks to this. Oyo could not maintain its cavalry army in the south but could raid at will. Cavalry in highly developed societies such as Oyo was divided into light and heavy. Heavy cavalry on larger imported horses was armed with heavy thrusting lances or spears and also with swords. Light cavalry on smaller indigenous ponies was armed with clubs. Infantry Infantry in the region around the Oyo Empire was uniform in both armour and armament. All infantry in the region carried shields, swords and lances of one