heavy and had to be constantly cleaned to prevent rusting; in direct sunlight, metal armour became unbearably hot. Conquistadores often went without metal armour, or only donned it immediately prior to battle. They were quick to adopt quilted cotton armour based upon that used by their native opponents, and commonly combined this with the use of a simple metal war hat. Shields were considered essential by both infantry and cavalry; generally this was a circular target shield, convex in form and fashioned from iron or wood. Rings secured it to the arm and hand. Role of the Church The justification for conquest was explicitly religious. In 1493, the Spanish Pope Alexander VI issued the Bulls of Donation that justified the colonisation of the New World for the express purpose of converting the native inhabitants to Christianity. The Spanish Crown and the Church insisted that the conquered peoples were human souls meriting legal rights and protection, while the colonists claimed they were subhuman, and a valid resource for forced labour. These opposing viewpoints led to conflict between the authorities in Spain and the colonists on the ground in the Americas. There was religious participation in the conquest of Nicaragua from the first exploratory expeditions onwards; Father Diego de Agüero accompanied Gil González on his 1519 expedition, and returned with Francisco Hernández de Córdoba in 1524, with two religious companions. One of the first actions performed upon entering an indigenous settlement was to plant a cross on top of the local shrine, to symbolically replace the native religion with the authority of the Church. Fathers Contreras and Blas Hernández established the first Jesuit presence in 1619. Discovery of Nicaragua, 1519–1523 Spanish explorers first viewed the Pacific coast of Nicaragua in 1519, sailing up from Panama. That year, Pedrarias Dávila executed Vasco Núñez de Balboa and seized his ships on the Pacific coast of Panama. He put Gaspar de Espinosa in command of two ships, San Cristóbal and Santa María de la Buena Esperanza, and sent him to scout westwards. Espinosa disembarked at the Burica Peninsula, on the modern border between Panama and Costa Rica, to return overland to Panama. The two ships continued along the coast, under the command of Juan de Castañeda and Hernán Ponce de León. They discovered the Gulf of Nicoya, probably on 18 October of that year, which became the key entry route to Nicaragua for later expeditions.