Dennis Dwyer was born in the Parish of Fethard, County Tipperary, Ireland, February 3, 1830. He emigrated to the United States when about fifteen years of age. For a while he worked at farming; came to Dayton in 1850; learned the cabinet-making business; afterwards worked at pattern-making, and made the patterns for the first steam engine in the United Brethren printing establishment in Dayton. He read law with the late firm of Wood & Nead, and was admitted to the bar in 1856; has for a long time taken an active part in local State politics; was for a while with the late Hon. C. L. Vallandigham and James Kelly, one of the proprietors and publishers of the Dayton Empire and Ledger; has served for several years as Chairman of the Democratic Central Committee of Montgomery County, and once as a member of the Democratic State Central Committee; was elected Probate Judge of Montgomery in the fall of 1866; again in the fall of 1869; and re-elected for a third time in the fall of 1872, and is now filling the office. He originated, about five years ago, the Irish Catholic Benevolent Union of the United States, a union of societies for benevolent and charitable purposes, which has since spread over twenty-three States and Territories of the United States.