The second Lateran, and tenth ecumenical council was held by Pope Innocent II in April 1139, and was attended by close on a thousand clerics.
Its immediate task was to neutralize the after-effects of the schism, which had only been terminated in the previous year by the death of Antipope Anacletus II (d. January 25 1138). All consecrations received at his hands were declared invalid, his adherents were deposed, and King Roger II of Sicily was excommunicated. Arnold of Brescia, too, was removed from office and banished from Italy.
This entry was originally from the 1911 Encyclopedia Britannica.
The council was also significant for its outlawing the use of crossbows in wars between Christians. This was arguably the first international law against inhumane conduct.
