Viscount Decies is a title that has been created twice in the Peerage of Ireland

Peerage of Ireland

The Peerage of Ireland is the term used for those titles of nobility created by the English and later British monarchs of Ireland in their capacity as Lord or King of Ireland. The creation of such titles came to an end in the 19th century. The ranks of the Irish peerage are Duke, Marquess, Earl,...

. The first creation came on 31 January 1569 in favour Maurice Fitzgerald, Baron of Dromana. He had already been created Baron of Dromana on 27 January 1569, also in the Peerage of Ireland. This creation became extinct on his death in 1572. The second creation came on 9 October 1673 in favour of Richard Power, 6th Baron Power. See Earl of Tyrone

Earl of Tyrone

The Earl of Tyrone is a title created three times in the Peerage of Ireland.It was first created as part of the Tudor attempt to establish a uniform social structure in Ireland by converting the Gaelic kings and chiefs into hereditary nobles of the Kingdom of Ireland...

for more information on this creation.