Cross of Burgundy
The year 1506 should be considered its theoretical earliest use in Spain (that is, it made appearance on the standards carried by Philip the Handsome's Burgundian life guards), although about 1525 might be perhaps a more likely estimate. Philip, after his marriage to Joanna of Castile, became the first Habsburg King of Spain and used the Cross of Burgundy as an emblem as it was the symbol of the house of his mother, Mary of Burgundy. From the time of Philip and Joanna's son, Emperor Charles V (King Charles I of Spain), different armies within his empire used the flag with the Cross of Burgundy over different fields. Nevertheless, the official field was still white. The Spanish monarchs – the Habsburgs and their successors' the House of Bourbon – continued to use the Cross of Burgundy in various forms, including as a supporter to the Royal Coat of Arms. From the time of the Bourbon king Philip V (1700–1746), it seems that the Spanish naval ensign was white and bore a royal coat of arms in the centre, though it is said that the Burgundian flag was still flown as a jack ensign, that is, as a secondary flag, until Charles III introduced his new red-yellow-red naval ensign in 1785. It also remained in use in Spain's overseas empire (see #Overseas Empire of Spain below).