Complex sentence: He was called to the Irish bar in 1790, and quickly obtained a practice, principally as counsel for prisoners charged with political offenses, becoming the legal adviser of the Society of the United Irishmen.
Split into simpler sentences: He was called to the Irish bar in 1790 and quickly obtained a practice, principally as counsel for prisoners charged with political offenses. He also become the legal adviser of the Society of the United Irishmen.