After Nguyễn Ánh established the Nguyễn dynasty in 1802, he tolerated Catholicism and employed some Europeans in his court as advisors. His successors were more conservative Confucians and resisted Westernization. The next Nguyễn emperors, Minh Mạng, Thiệu Trị, and Tự Đức brutally suppressed Catholicism and pursued a 'closed door' policy, perceiving the Westerners as a threat, following events such as the Lê Văn Khôi revolt when a French missionary, Fr. Joseph Marchand, was accused of encouraging local Catholics to revolt in an attempt to install a Catholic emperor. Catholics, both Vietnamese and foreign-born, were persecuted in retaliation. Trade with the West slowed during this period. There were frequent uprisings against the Nguyễns, with hundreds of such events being recorded in the annals. These acts were soon being used as excuses for France to invade Vietnam. The early Nguyễn dynasty had engaged in many of the constructive activities of its predecessors, building roads, digging canals, issuing a legal code, holding examinations, sponsoring care facilities for the sick, compiling maps and history books, and exerting influence over Cambodia and Laos.