SUMMARY Juan Baptista de Segura was a priest and vice-provincial of the Jesuits in the Spanish province of La Florida. In 1570 he led a mission to the Chesapeake Bay and was killed the next year in an ambush led by Don Luís de Velasco (formerly Paquiquineo), a Virginia Indian who had converted to Christianity. Born in Toledo and educated at a time when Spanish clerics vigorously debated the best way of converting American Indians, Segura joined the Society of Jesus in 1556 and was ordained a priest the following year. Ten years after that he was named vice-provincial of the Jesuits in La Florida. An intellectual and idealist, Segura was also an indecisive leader who advised his superior that the Jesuits should abandon La Florida and then, just a few months later, organized a mission to the Chesapeake Bay. Segura insisted, against the advice of Florida governor Pedro Menéndez de Avilés, that the Jesuits did not need military protection on their mission. He instead placed his faith in Don Luís, who promised that the land he called Ajacán would be rich in potential converts and natural resources. Segura established his mission near the mouth of the Chesapeake Bay in September 1570, but when Don Luís returned to his family, the Jesuits were without support. In February 1571 the Virginia Indian killed Segura and his fellow missionaries, leaving only an altar boy alive.