The association of James as the patron saint of Spain has no basis in the bible, but exists on the realm of tradition, oral history, legend and myth.
The story goes that James preached in Ileberia a message of faith with particular emphasis on faith without works being dead or action in faith speaks louder than words, if you will. Apparently, he was not very successful, recruiting only seven disciples in his seven years of preaching. The last we hear of James is the biblical account is his martyrdom at the hands of Herod Agrippa in Rome around the year 44CE (acts 22:12).
The legend says James body was transported to Spain on a stone ship without oars or sail, viking style, carried by angels and the wind. The ship landed at Iria Flavia (Padron) and James disciples met the ship there and carried his body to a nearby hill where he was buried. The body of James appears to have been forgotten for the next seven and a half centuries until 813 when Christian hermit named Pelayo saw a shining light down on Mount Libredon that led to the grave of St.James, along with the remains of two of his disciples, Atanasio and Teodoro.
The bishop authenticated the relics and king Alfonso11 built a chapel to the saint, which drew a modest number of pilgrims. In 1075 the cathedral de Santiago was commenced and the current Cathedral was completed in 1120 where the remains of St.James are encased in a tomb behind the main alter for pilgrims to pay homage.
The Camino de Santiago was for many travelers, now called pilgrims, a long and tireless journey. Coming from France, Germany, Portugal & many other European nations as well as Spain to pay homage to the saint and seek indulgences.
At the peak of Santiago’s attraction as a place of pilgrimage during the Middle Ages, from the 9th to the 16th century, up to two million people, around 5000 per day came to visit the burial place of St. James.The reformation in Europe and Spain’s war with England saw the decline of Santiago as a place of pilgrimage. The scallop shell remains the symbol, of the Camino with its outer shell representing the many routes that lead to Santiago and the inner shell, the hand of friendship and help. It has been used for centuries to denote that an individual displaying the shell is on a pilgrimage and is protected. Historical the Knights Templar, of the order of St. James, whose symbol is a red sword, protect the pilgrim on the road against thieves and vagabonds.
The Camino de Santiago may auspiciously be a Christian experience, many people from
other faiths (or no faith) walk the path and did also in medieval times. The event that captured the modest shrine of St.James was at the battle of Clavigo against the Muslim invaders. James was said to appear arriving on a white horse with the red sword of the Templar above his head leading the Spanish knights to beat the moors in battle.
This image of St.James was a convenient motif to draw Christian support to the frontier of the Christian-Muslim battler and to bolster financial investment in Christian domination of Iberia. It is said the Christian scattered some of James ashes in the battle, whilst the Muslims had a mummified arm of Mohammad in a cloth as a guiding symbol.
Whilst the legend lives on that St.James appearance in the battle field at Clavijo was a direct result of the Christians regaining the upper hand in Spain, it is just a story. In fact, St.James, to the best of scholars seem to agree, never came to Spain. There is no earthly reason why his body should be brought to Galicia and nothing suggest this in the Acts of the Apostles, where his death is recorded. He died several centuries before Islam was conceived, probably never mounted a horse in his life and certainly never slew an infidel. There is no earthly reason Santiago should be a place of pilgrimage, though it is.