Unfortunately, the DT entry names no source for the tune, which is very similar to the example in Stanford-Petrie mentioned below, though the note-values differ. It had nothing much to do with Archibald Scott, of course. The following two references are taken from David Kuntz's  The Fiddler's Companion:

VIVE LA! (THE FRENCH ARE COMING).  Irish, March (2/4 time, "with spirit"). D Major (Roche): C Major (Stanford/Petrie). Standard. AB (Stanford/Petrie): AAB (Roche).
The tune is a march version of the air usually known as "Loch Erroch Side," "I'm Ower Young to Marry Yet," "Over the Hills to Glory," "The Lass of Gowrie," or "The Lakes of Sligo." The title refers to the hoped-for intervention of French troops on the side of the Irish in the rebellion of 1798.
Stanford/Petrie (Complete Collection), 1905; No. 996, pg. 254. Roche Collection, 1982, Vol. 3; No. 46, pg. 13.

CLARE(S) DRAGOONS.  Irish, English; Polka. D Mixolydian ('A' part) & D Major ('B' part) [Carlin]: D Major [Mallinson]. Standard. AABB.
County Clare takes its name from the 12th century leader of a Norman conquering expedition, Gilbert de Clare, nicknamed Strongbow.
Carlin (Master Collection), 1984; pg. 154, No. 273. Mallinson (100 Polkas), 1997; No. 48, pg. 19. Raven (English Country Dance Tunes), 1984; pg. 152.

T:Clare's Dragoons
L:1/8
M:2/2
K:D
AG|F2A2A2Bc|d3e d2A2|F2A2A2d2|edcB AGFE|
F2A2A2 Bc|d3e defg|a2A2A2f2|e3d d2:|
|:e2|f2a2e2f2|d3ef2d2|f2a2e2f2|gfed G2e2|
f2a2e2f2|d3e defg|a2A2A2f2|e3d d2:|

The tunes are essentially the same. Another song set to Vive La can be seen at the Bodleian: The Irishman: To the tune of: Vive La  Haly Printer south Main street Cork, 18--

There is also a lyric by James Connolly, Human Freedom, set to Clare's Dragoons: Lyr Add: The Songs of James Connolly

Robert Burns set songs to two of the earlier forms of the melody mentioned above: A Song. -On Miss P- K-. (Loch Eroch Side) in 1784/5 and I'm o'er young to Marry Yet in 1788.