Irish Political History series 
Irish nationalism is associated with the Irish Catholic community, but the cause has historically been supported by many Irish Protestant nationalists.
Ireland has been subject to varying degrees of rule from England since the late 12th century (See Norman Ireland). The Gaelic Irish resisted this conquest through military and other means, but were organised in small independent lordships and did not have a common political goal such as an independent Irish state. Conflict over the English presence was exacerbated by the Protestant Reformation in England, which introduced a religious element to the 16th century Tudor re-conquest of Ireland, as almost all of the native Irish remained Catholic. In Ireland, many native Catholic landowners were dispossessed during the Plantations of Ireland when land was given to Protestant settlers from England and Scotland[1]. In addition, the Plantation of Ulster, begun in 1609, "planted" a sizable colony of English and Scottish settlers into the north of Ireland.
The closest Gaelic lords came to waging an identifiably nationalist campaign against the English presence was the rebellion of Hugh O'Neill in the 1590s (known as the Nine Years War 1594-1603), which aimed to expel the English and make Ireland a Spanish proctorate[2]. However, despite claiming to represent a movement of Irish Catholics against English Protestants, O'Neill's forces were a shifting coalition of clans and lords and many historians see O'Neill himself as being primarily motivated by personal ambition - specifically the securing of his authority over Tyrone in Ulster[3].