The Union-Jack
The term “Union-jack” is one which is partly of obvious signification, and in part somewhat perplexing. The “Union” between England and Scotland, to which the flag owed its origin, evidently supplied the first half of the compound title borne by the flag itself. But the expression “jack” involves some difficulty. Several solutions of this difficulty have been submitted, but, with a single exception only, they are by far too subtle to be considered satisfactory. A learned and judicious antiquary has recorded it as his opinion, that the flag of the Union received the title of “Union-jack” from the circumstance of the union between England and Scotland having taken place in the reign of King James, by whose command the new flag was introduced. The name of the king in French, “Jaques,” would have been certainly used in heraldic documents: the union flag of king “Jaques” would very naturally be called after the name of its royal author, Jaques’ union, or union Jaques, and so by a simple process we arrive at union-jack. This suggestion of the late Sir Harris Nicolas may be accepted without any hesitation; and the term “jack” having once been recognised as the title of a flag, it is easy enough to trace its application to several flags. Thus the old white flag with the red cross is now called the “St. George’s jack;” and English seamen are in the habit of designating the national ensigns of other countries as the “jacks” of France, Russia, &c.
We quote this sensible view from the Art Journal. The paper by Sir Harris Nicolas above referred to will be found in the Naval and Military Magazine for 1827; and with engravings, in Brayley’s Historic and Graphic Illustrator.