In 1667, Penn left Lincoln’s Inn, traveling to Ireland to settle a lawsuit over the family estate. Penn also served as a military aide during the insurrection of disgruntled soldiers at Carrickfergus, action in which he distinguished himself. His success spurred him to pursue a career in the military, but he was denied a position in the army. It was during this time that Penn became a Quaker. He had long been acquainted with Quaker beliefs, but it was while he was in Ireland, under the influence of Thomas Loe, a disciple of the Society of Friends’ founder George Fox, that Penn converted. Penn quickly became a defender of his fellow Quakers and their beliefs. His publication of Sandy Foundations Shaken, a pamphlet that was part of an ongoing debate with Thomas Vincent, a Presbyterian minister, resulted in his imprisonment in the Tower of London for libel. Refusing to recant, Penn remained in prison for seven-and-a-half months until his father petitioned the Privy Council for his release. Penn authored 150 books and pamphlets over the course of his life, writings in which he consistently argued for toleration of nonconformity. Penn believed that a person’s conscience belonged only to God, a belief for which toleration was an absolute necessity. On April 4, 1672, Penn married Gulielma Maria Springett. They had seven children, four of whom died in infancy. Only Springett, Letitia, and William (Billy) survived to adulthood. In 1675, Penn became a trustee for the colonial venture in New Jersey. While this was not a wholly Quaker colony, many members of the sect were involved in its ownership and settling. Penn helped to frame the constitution for the colony in a document entitled Concessions and Agreements.