Final answer:
Charles V of Spain engaged in wars during his reign largely to maintain the supremacy of Catholicism and to defend his empire, which included the Holy Roman Empire, Spain, and the American colonies.
Step-by-step explanation:
During his reign, Charles V of Spain engaged in various wars to defend and propagate the Catholic faith as well as to maintain his extensive empire that included not just Spain but also the Holy Roman Empire and his American colonies. His son, Philip II, continued these efforts vigorously, battling against Calvinist rebels in the Spanish Netherlands and attempting to restore Catholicism in England through the ill-fated Spanish Armada.
Throughout his reign, Charles was involved in numerous conflicts across Europe and the New World. By marriage and direct inheritance, he ruled a vast realm that required constant defense and led to conflicts such as the War of the Spanish Succession and battles against Protestant forces in the growing religious turmoil that included the Reformation and the subsequent Counter-Reformation.
These wars were driven by both the defense of Catholicism and the desire to maintain territorial integrity and supremacy within Europe, resulting in a turbulent period marked by widespread conflict.