This famous Irish surname recorded in such diverse spellings as O'Mahon, Mahon, Moan, Moen, Mowne, Mohun, Mowen, Maughan and Vaughan, has two possible derivations. The first is from the ancient Gaelic O'Mochain, apparently translating as "the son of the descendant of the early one" a reference to the first chief, whilst the second is of Norman origins, and derives from the "de Mohun" family, who accompanied Strongbow, earl of Pembroke, on his original expedition to Ireland in the year 1169. There are now two separate clans or septs, one in Connacht, the other in Munster, where to add confusion the name is usually spelt Vaughan. In County Galway, the name is most usually spelt as Mahon, although sometimes as Maughan or Mahan. In County Roscommon in the 13th century the clan were "erenaghs" or hereditary lords, responsible for the upkeep of the church and church property in their region. The transmutation of the surname from Mochain or Moghan to Vaughan, a Welsh surname, which arrived in Ireland in its own right before the 15th century, and which occurred particularly in counties Cork, Limerick and Clare, is one of life's little curiosities. The name spelling as Moan, Mowen, etc. is most popular in Ulster. Amongst the early recordings are those of Denis Mahan, the American soldier (1802 - 1871) whose parents emigrated from Ireland in 1802, and his son Alfred, the leading American naval historian (1840 - 1914). The first known recording of the family name is probably that of Gregory O'Moghan, the Archbishop of Tuam, Ireland, who died there in the year 1392. Surnames have continued to "develop" over the centuries, often leading to some amazing variants of the original spellings.