sentences:  The mental strain to which O'Mahony was subjected in the preparation of this work, which brought him no pecuniary gain, affected his reason, and he was removed by his friends for a short time to a lunatic asylum.In 1858, O'Mahony organised the Fenian Brotherhood in the U.S.A., closely associated with the Irish Republican Brotherhood in Ireland.The object of the association was to secure the separation of Ireland.