Why were the Spanish interested in extending their claim into North America? A. Years after the explorations of de Soto and others, most Spanish suit believed there were vast stores of gold yet to be discovered, A. They wanted to get revenge on the French and other powers by establishing bases from which they could attack trading ships, C. Bases and missions further north would help protect their land daims and trans ocean shipping from European rivals, D. Spain was late to the Atlantic Slave Trade because of the success of American Indian enslavement and indenture.​