Show ContentsO'Casidy History, Family Crest & Coats of Arms

Irish names tend to vary widely in their spelling and overall form. The original Gaelic form of the name O'Casidy is Ó Casaide. 1

Early Origins of the O'Casidy family

The surname O'Casidy was first found in Fermanagh (Irish: Fear Manach) in the southwestern part of Northern Ireland, Province of Ulster, where the Irish sept claims direct descent from the Irish King Colla da Crioch who was banished from Ireland in 327. 2

Early History of the O'Casidy family

This web page shows only a small excerpt of our O'Casidy research. Another 96 words (7 lines of text) covering the years 1143 and 1740 are included under the topic Early O'Casidy History in all our PDF Extended History products and printed products wherever possible.

O'Casidy Spelling Variations

The recording of names in Ireland during the Middle Ages was an inconsistent endeavor at best. Since the general population did not know how to read or write, they could only specify how their names should be recorded orally. Research into the name O'Casidy revealed spelling variations, including Cassidy, Cassady, Cassiday, Cassedy, Cassedey and others.

Early Notables of the O'Casidy family

More information is included under the topic Early O'Casidy Notables in all our PDF Extended History products and printed products wherever possible.

Migration of the O'Casidy family

Death and immigration greatly reduced Ireland's population in the 19th century. For the native Irish people poverty, hunger, and racial prejudice was common. Therefore, thousands left their homeland to seek opportunity in North America. Those who survived the journey and the quarantine camps to which they arrived, were instrumental towards building the strong developing nations of the United States and the future Canada. By far, the largest influx of Irish settlers occurred with Great Potato Famine during the late 1840s. These were employed as construction or factory workers. An examination of passenger and immigration lists has shown early immigrants bearing the name O'Casidy: Patrick Cassidy who settled in Rhode Island, and later moved to Norwich in Connecticut, where he became one of America's first surgeons. Edward, Hugh, James, John, Patrick, Thomas and William Cassady who all arrived in Philadelphia between 1840 and 1865.



The O'Casidy Motto +

The motto was originally a war cry or slogan. Mottoes first began to be shown with arms in the 14th and 15th centuries, but were not in general use until the 17th century. Thus the oldest coats of arms generally do not include a motto. Mottoes seldom form part of the grant of arms: Under most heraldic authorities, a motto is an optional component of the coat of arms, and can be added to or changed at will; many families have chosen not to display a motto.

Motto: Frangas non flectes
Motto Translation: Thou may'st break, but shalt not bend me.


  1. MacLysaght, Edward, Irish Families Their Names, Arms and Origins 4th Edition. Dublin: Irish Academic, 1982. Print. (ISBN 0-7165-2364-7)
  2. O'Hart, John, Irish Pedigrees 5th Edition in 2 Volumes. Baltimore: Genealogical Publishing Company, 1976. Print. (ISBN 0-8063-0737-4)


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