His public opposition to the newly Protestantized Church of England forced him to leave the country, and in 1561, after resigning his benefices, he left England to seek refuge at Louvain and its University, where he joined many other academics from Oxford and Cambridge who had refused to take the Oath of Supremacy. There, he continued his theological studies and began to write apologetic, polemic, and controversialist treatises. In the following year, because of ill health, he was advised to return to his native Lancashire. He devoted himself to the re-conversion of his native land to the old faith. In particular, he worked to dissuade the Roman Catholic faithful from attending Anglican worship, an outward compromise of their faith and conscience that many made, to avoid ruin from fines, confiscations, and other disabilities.