For centuries the flag of England was the red cross of St. George on a white field. Likewise, for centuries the flag of Scotland was the white cross of St. Andrew on a blue field. In 1603 England and Scotland, after many years of warfare, united under King James I, and it became necessary to devise a flag which would typify that union. This was done in 1606 by blending the two crosses together. The Scottish flag was retained as the background for the new banner and the cross of St. George superimposed on it. To retain a semblance of the white field of the English flag, the red cross of St. George was mounted on a strip of white which extends out and beyond the borders of the cross, and this makes it prominent and distinct.
The new flag was variously called the King’s Colors or the Grand Union Flag. It is the banner under which the English colonization of America was effected, and remained the flag of the colonists for more than 100 years.