His feast day is celebrated on July 25.
Many people believe James went to Spain and preached Christianity there for a time before returning to Judea, where he was beheaded by King Herod Agrippa I in the year 44. Another tradition states that he miraculously appeared to fight in a Spanish army during the Reconquista, and is therefore called Matamoros (Moor-slayer). Santiago y cierra España ("St James and close Spain", it's not totally grammatical in Spanish) has been the battle cry of Spanish armies. St Emillianus (san Millán) is said to appear in a battle as well.
The military Order of Santiago or caballeros santiaguistas was founded to fight the Moors and later membership became a precious honour. People like Diego Velázquez longed for the royal favour that allowed to put on their clothes the red cross of St. James (similar to an obelus, †).
These traditions are the main reason James became the patron saint of Spain, and his shrine at Santiago de Compostela, in Galicia in Spain, became the most famous pilgrimage site in the Christian world. St James's Way is a set of routes that cross Western Europe and arrive to Santiago through Northern Spain.
The name "James" in English comes from "Iacobus" (Jacob) in Latin. In eastern Spain, Jacobus became "Jacome" or "Jaime"; in western Spain it became "Iago". "Saint James" ("Sanctus Jacobus") became "Sant' Iago", which was abbreviated to Santiago, and then by false etymology broken into San Diego. James's emblem was the scallop shell (or "cockle shell"), and pilgrims to his shrine often wore that symbol on their hats or clothes. The French for a scallop is coquille St. Jacques, which means "cockle (or mollusk) of St. James", and that term also refers to a method of cooking and serving them, on a shell (real or ceramic) in a creamy wine sauce.St James and Spain