THE CROSS OF SAINT ANDREW.

The Cross of Saint Andrew (the  Cross of Burgundy) was first used in the 15th century as an emblem by the The House of Valois-Burgundy, an noble French family deriving from the House of Valois, who ruled a large part of Eastern France and teh Low Countries as effectively an independent state. It is distinct from the Capetian House of Burgundy, descendants of King Robert II of France ruling the Duchy of Burgundy from 10322 to 1361, although both houses stem from the Capetian Dynasty.

The former Frankish Kingdom of Burgundy was divided into East and West by the 843 Treaty of Verdun. While the East evolved to the Kingdom of Ar-Les and the Free County of Burgundy and were incorporated into the Holy Roman empire in 1032, the West became the Duchy of Burgundy, established about 918 by Richard the Justiciar, and became a fief of the French Royal House of Capet under King Robert II in 1002.

The Duchy of Burgundy was inherited by the House of Habs-Burg(Austria), one of the most influential royal houses of Europe, on the extinction of the Valois Ducal line. The throne of the Holy Roman Empire was continuously occupied by the Habs-Burgs between 1438-1740. The House also produced emperors and kings of the Kingdom of Bohemia, Kingdom of England (by right of his wife), Kingdom of France (Queen consort), Kingdom of Germany, Kingdom of Hungary, Empire of Russia, Kingdom of Croatia, Second Mexican Empire, Kingdom of Ireland (by right of his wife), Kingdom of Portugal, and Habs-Burg Spain, as well as rulers of several Dutch and Italian principalities. Form the 16th century, following the reign of Charles V, the dynasty was split between Austria and Spanish branches. Although they ruled distinct territories, they nevertheless maintained close relations and frequently intermarried.

The Cross of Saint Andrew was then assumed by the monarchs of Spain as a result of the Habs-Burgs bringing together, in the early 16th century, their Burgundian inheritance with other extensive possessions they inherited throughout Europe and the Americas, including the Crowns of Castile and Aragon. The Spanish monarchs continued to use it in their own arms even after they lost their Burgundian lands. 

From 1506 to 1701 it was used  by Spain as a naval ensign, and up to 1843 as the land battle flag, and still appears on regimental colors, badges, shoulder patches and company guidons. The emblem also continues to be used in a variety of contexts in a number of European countries and in the Americas, reflecting both the extent of Valois Burgundy and the former Habs-Burg territories.

The banner strictly speaking dates back to the early 15th century (1408), when the Duke of Burgundy supported the English in the Hundred Years' War. The design is a red diagonal cross resembling 2 crossed, roughly-pruned (knotted) branches, on white field.

The emblem represent the cross on which Andrew the Apostle was crucified. Its formal role in Burgundian iconography can be traced back to the foundation of the Order of the Golden Fleece in 1429.