The Knights of Saint John, also known as the Knights Hospitaller, is a medieval Catholic military order founded in the 11th century. Initially established to provide care for sick and injured pilgrims in the Holy Land, the order evolved into a military force during the Crusades, defending Christian territories. Over the centuries, the Knights of Saint John expanded their influence, acquiring territories and establishing hospitals across Europe. They played a significant role in the defense of Malta after the Great Siege of 1565, which solidified their reputation as formidable warriors. Today, the order continues to exist as a charitable organization.