"The St. James cross symbolizes the fighting spirit of true Christianity when faced with an existential threat, such as was posed to Christian Europe by the 8th Century Islamic invasion from North Africa. By the 9th century, only a narrow strip of northern Spain was still in Christian hands, and the Mohammedan invaders were poised to complete their conquest of the Iberian peninsula and move onward into Christian France. The miraculous (some would say legendary) appearance of St. James on a white horse with a flashing sword held high marked the beginning of the Christian reconquest of Spain. The St. James cross became the rallying symbol of the fighting Christians who refused to submit to Islamic conquest, but instead went on the offensive to eject them from Spain." - Matt Bracken
The insignia of the order is a red cross with three fleur-de-lis (on the hilt and arms). The three fleurs-de-lis represent "honor without stain" - a descriptor of St. James' character.