The English Catholic apologist John Heigham (1568–1632) deserves to be better known in light of the significant historical consequences of his efforts in the field of Catholic apologetics. Heigham’s tract, The Gagge of the Reformed Gospel (1623) accused the Reformed Church in England of heresy and innovation and summoned the readers back to the Roman Catholic Church. This work was answered by Richard Montagu (1577–1641), the future bishop of Chichester and Norwich in his book, A New Gagg for an Old Goose (1624). Montagu’s book provoked a storm of controversy within the Church of England because the author simultaneously replied to Heigham’s Catholic arguments and attacked Calvinism within the Church of England, which he labelled ‘Puritanism’. A series of books attacking Montagu were then published by English Calvinists who accused Montagu of popery and of betrayal of the Reformed cause. These disputes contributed to the Calvinist/Arminian division within the Anglican Church, a religious controversy that was one of the contributing causes of the English Civil War. Thus the seed planted by Heigham’s tract grew into a forest of religious controversies and ended in a war. This article summarizes the content of Heigham’s tract and the principal ideas of his Catholic apologetics, after recounting the main events of Heigham’s little known life. Then Montagu’s response will be surveyed and the reactions it spawned.