Show ContentsO'Casidie 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'Casidie is Ó Casaide. 1

Early Origins of the O'Casidie family

The surname O'Casidie 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'Casidie family

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

O'Casidie Spelling Variations

Within the archives researched, many different spelling variations of the surname O'Casidie were found. These included One reason for the many variations is that scribes and church officials often spelled an individual's name as it sounded. This imprecise method often led to many versions. Cassidy, Cassady, Cassiday, Cassedy, Cassedey and others.

Early Notables of the O'Casidie family

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

Migration of the O'Casidie family

To escape the religious and political discrimination they experienced primarily at the hands of the English, thousands of Irish left their homeland in the 19th century. These migrants typically settled in communities throughout the East Coast of North America, but also joined the wagon trains moving out to the Midwest. Ironically, when the American War of Independence began, many Irish settlers took the side of England, and at the war's conclusion moved north to Canada. These United Empire Loyalists, were granted land along the St. Lawrence River and the Niagara Peninsula. Other Irish immigrants settled in Newfoundland, the Ottawa Valley, New Brunswick and Nova Scotia. The greatest influx of Irish immigrants, however, came to North America during the Great Potato Famine of the late 1840s. Thousands left Ireland at this time for North America and Australia. Many of those numbers, however, did not live through the long sea passage. These Irish settlers to North America were immediately put to work building railroads, coal mines, bridges, and canals. Irish settlers made an inestimable contribution to the building of the New World. Early North American immigration records have revealed a number of people bearing the Irish name O'Casidie or a variant listed above, including: 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'Casidie 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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