The County of Coleraine, also known as County Coleraine, was a county of Ireland. It was the only one of the original counties of Ireland to be abolished before the twentieth century (but ceased to exist before, for example County Wicklow was created).
English control of the territory was nominal, so in 1607 almost the entire county was confiscated from its Irish aristocratic feudal owners, and in 1609, it was given to the City of London Corporation and its livery companies, who were commanded to undertake its plantation.
The area to be planted included:
the entirety of County Coleraine,
the barony of Loughinsholin which comprised the then north of County Tyrone and the environs of Coleraine in County Antrim, together called O'Cahan's Country,
In 1613, this larger area was incorporated into the new County Londonderry, with its county town in new walled city of Londonderry on the west bank of the Foyle, opposite the destroyed town of Derry.