Regiment of Hibernia
The Regiment of Hibernia, was one of the Spanish army´s regiments. Known by many in Spain as "O'Neill's Regiment", it was formed in 1710 from Irishmen who fled their own country in the wake of the Flight of the Earls and the penal laws and who became known as the Wild Geese a name which has become synonymous in modern times for Irish soldiers throughout the world.
Although the Wild Geese are more associated with the French Army and are indeed seen as the precursors of the French Foreign Legion the regiment  of Hibernia was one of many Irish regiments to serve in the Spanish army. The Wild Geese began fighting for Spain during Eighty Years' War as the first Irish units in the service of Spain were formed in 1587.
Due to the number of wars Spain was involved in during the early 18th century the country could not provide itself with enough soldiers for its own campaigns. This was also exacerbated by the severe loss of manpower as a result of a plague epidemic. Diplomatic approaches were made to a number of countries with requests for the recruitment of mercenaries to fight for Spain.
Germans, Italians and Walloons were recruited but the Spanish were particularly keen to engage Irishmen because of their reputation as soldiers. The Confederation of Kilkenny established licences for the recruitment of Irishmen to fight with the King of Spain.
One remarkable facet of so many Irishmen fighting for opposing nations in Europe was that they occasionally faced each other as enemies on foreign battlefields.
Campaigns and battles
- Battle of Zaragoza (1710)
- Battle of Brihuega
- Battle of Villaviciosa
- Siege of Barcelona (1714)
- Siege of Gibraltar
- Ceuta (1720–1721)
- Brazil (1777)
- Jamaica (1780)
- Battle of Pensacola (1781)
- Irish Brigades Abroad, Stephen McGarry
- The Spanish Monarchy and Irish Mercenaries.- The Wild Geese in Spain 1618-68. (R.A. Stradling)
- The Irish Brigades in the Service of France, J.C. O'Callaghan.
- The Wild Geese, M. Hennessy
- The March of O'Sullivan Beare, L.J. Emerson.
- The O' Neills in Spain, Spanish Knights of Irish Origin, Destruction by Peace, Micheline Kerney Walsh. The Irish Sword, Vol 4-11
- The Wild Geese, Mark G. McLaughlin.
- Wild Geese in Spanish Flanders, 1582–1700, B. Jennings.
- Spain under the Habsburgs, John Lynch
- The Flight of the Earls, John McCavitt