Between 1615 and 1753, French traders also engaged in trade in Vietnam. The first French missionaries arrived in Vietnam in 1658, under the Portuguese ''Padroado''. From its foundation, the Paris Foreign Missions Society under ''Propaganda Fide'' actively sent missionaries to Vietnam, entering Cochinchina first in 1664 and Tonkin first in 1666. Spanish Dominicans joined the Tonkin mission in 1676, and Franciscans were present in Cochinchina from 1719 to 1834. The Vietnamese authorities began to feel threatened by continuous Christianisation activities. Following the detention of several missionaries, the French Navy received approval from their government to intervene in Vietnam in 1843, with the aim of freeing imprisoned Catholic missionaries from a kingdom that was perceived as xenophobic. Vietnam's sovereignty was gradually eroded by France in a series of military conquests between 1859 and 1885. At the Siege of Tourane in 1858, the French was aided by the Spanish (Using Filipino and Spanish troops from the Philippines) and perhaps some Tonkinese Catholics. After the 1862 Treaty and especially after the full conquest of Lower Cochinchina by France in 1867, the Văn Thân movement of scholar-gentry class arose and committed violence against Catholics across central and northern Vietnam.