An American Conversion
He gave up his ministerial credentials in the Protestant church and studied for the Catholic priesthood. He was ordained a priest in Europe and traveled back to the states where his conversion story made quite a stir in the New World. Such a thing as a Protestant becoming Catholic was unheard of particularly in the strongly anti-Catholic new nation where Catholics were not allowed to vote or hold public office! His desire for the rest of his life was to help others see the truth in the Catholic faith. He was less than successful as a diocesan priest in the states and eventually ended his ministry in Limerick Ireland where he passed away and left his estate back in Boston for a religious order of sisters. This was later burned down by an anti-Catholic mob in 1831.
His brother was a Protestant minister who apparently was less than enthused over his conversion.
Rev. John Thayer wrote down his conversion story as well as published a letter to his brother. His apologetics regarding papal infallability and discussion of sola scriptura are excellent and still stand the test of time. It is amazing that he was writing only 200 years after the reformation and identified the key issues that today's apologists still deal with.
Check out his book here. At 40 pages it is a quick read.