The Defenders were a Roman Catholic agrarian secret society in 18th-century Ireland, founded in County Armagh. Initially, they were formed as local defensive organisations opposed to the Protestant Peep o' Day Boys; however, by 1790 they had become a secret oath-bound fraternal society made up of lodges. By 1796, the Defenders had allied with the United Irishmen, and participated in the 1798 rebellion. By the 19th century, the organisation had developed into the Ribbonmen.