Which was true of European relationships in the 1500s?
Wars were common and alliances often shifted.
Wars were already common in Europe in the early part of the 16th century, such as the Habsburg-Valois Wars, which pitted the dynastic family of Spain & Austria vs. the dynastic family of France, with various Italiian states and England involved as well. The Protestant Reformation led to a series of additional, religiously-related wars, such as the Schmalkaldic War in German territories (1546-47), the English Civil Wars (1642-51) and the War of the Three Henrys (1587-89) for the throne of France.