This is another tune Doerflinger took down from Captain Henry E. Burke of Toronto, Ontario, and formerly Lunenburg, Nova Scotia. The tune is in the Dorian mode, a five-tone scale especially popular in folk airs from Britain and Ireland. Here's what Doerflinger had to write about the origins of the song:
The refrain is no doubt from the Civil War song "The Seven Days' Fight" ("Air-'Louisiana Lowlands'"), for which see The Arkansas Traveller's Songster (New York, Dick and Fitzgerald, 1864), p. 14. For "Louisiana Lowlands," see Minstrel Songs, Old and New (Boston, 1882), p. 72; the tune, however, is not related to Captain Burke's tune to "The Big Five Gallon Jar." His own title was "Cal and Jack, the Shanghaiers."
Jack Jennings was evidently a real, peg-legged, owner of a grog shop in Liverpool in the 1890s. Doerflinger quotes Burke:
His wife's name was Caroline. They were crimps. The large shipping ports had plenty of these characters in the palmy days of the square-rigged windjammer. Their victims was poor, unfortunate Jack, whom they lured into their dens... But the old, easy-going sailor thought these places were gay resorts... After having a few drinks, they knew no more. When they came to their senses, they found themselves in the fo'c'sle of a ship bound around Cape Horn or the Cape of Good Hope, to Australia, China, or San Francisco - shanhaied. And their worldly belongings consisted of the clothes they had on, a pound of tobacco, a belt, sheath and knife. Those were the days when sailors were made and the crimps reaped their harvest.
The song was adapted to other crimps, including Larry Meagher of New York.