First cousin of Henry Fitzsimons, James Ussher (1581-1656)
became a leading figure in the Church of Ireland, the official
Irish Protestant church. Unlike England and Scotland, in
Ireland most people remained Catholic despite Protestantism
being the legal religion.
In 1619 Ussher met and impressed King James I (of England, Ireland and Scotland). Rapidly promoted he became a key figure in arguing the case for Protestantism as the correct form of Christianity.
Ussher's closely argued and brilliantly written An answer to a challenge made by a Jesuite in Ireland was a reply to an earlier work by Irish Jesuit William Malone. The controversy itself was less noteworthy than the fact that this book made Ussher one of the best known and most influential Protestant writers in Europe.