Look up "Lisbon" in the DT database for a version collected in Somerset in 1904, where it says "Another Cruel War/Banks of the Nile variant". Percy Grainger collected a version in Lincolnshire in 1905 of which only the first verse verse survives:

T'was on a Monday morning, all in the month of May
Our ship she weighed her anchor, all for to sail away
The wind did from the south-west blow, for Lisbon we were bound
The hills and dales were covered with pretty young girls around

O'Shaughnessy's book of Grainger's Lincolnshire songs says:

"Lisbon" evidently originates from the time of the Napoleonic wars. The title suggests the Peninsular War 1808-14, but another version of the ballad entitled "The Banks of the Nile" refers to the earlier expedition against the French in Egypt in 1801.

So both UK and US versions refer to roughly the same time period (1800-15). Can anyone trace it further back?

For an Australian version see "The Banks of the Condamine" in the DT

Grainger's tune is completely different to the Battle of New Orleans, and is allegedly related to the Lincolnshire poacher. He used it not only in his "Lincolnshire Posy", but also in an arrangement for 5 saxophones and another (lost) for flute, oboe, clarinet, horn and bassoon

O'Shaughnessy says "The tune is in the Mixolydian mode, and, though repetitive, has great character... It moves about in a decidely non-harmonic manner, especially in the way it seems deliberately to avoid at first the mediant of the of the tonic triad. [me no comprende] Te art of the English folk singer, as Cecil Sharp demonstrated .... is generally not conditioned by awareness, conscious or otherwise, of harmonic implications.

(I think this means - don't ask for the chords, 'cos ther ain't none with this song)

X: 1
T:Lisbon
M:6/8
L:1/8
Q:1/4=140
K:DMix
G|A2B A2E|D3 D2E|F2D G2F|D3-D2 G|
A2B A2E|D3 D2E|F2D G2F|D3-D2 E|
F2G A2d|d2c A2B|c2d c2A|G3-G2 G|
A2B A2E|D2C D2E|FFD G2F|D3-D2||

Wassail! V