I made this note for my personal songbook (under the title The Coasts of Barbary) a few years ago. Much of the information was from a previous Mudcat thread.

" The song has apparently evolved from two related ballads. The records of the Stationers’ Company, where publishers had to register their broadsides, has this entry for 31st July 1590, apparently recording the composition of the first part of the original song, “A Dittye of the fight upon the seas the 4 of June last in the Straytes of Jubraltare betwene the ‘George’ and the ‘Thomas Bonaventure’, and viij Gallies with three Freggates”. According to a note in The Roxburghe Ballads (volume 6 at page 408) the song seems to have been current early in the 17th century.

Although the ballad is lost, Roy Palmer tells us that a fragment was quoted in The Two Noble Kinsmen of 1613. It begins

The George Alow came from the south, / from the coast of Barbary-a, / and there he met with brave gallants of war / by one, by two, by three-a.

The second ballad involved was based on that of 1590. The Stationers’ Company records that in March 1611 a publisher registered “Captayne Jenninges his songe, which he made in the Marshalsey [a prison in Southwark] and songe a little before his death; Item. The seconde part of the ‘George Aloo’ and the ‘Swiftestake’, being both ballads.”

John Jennings knew very well the brutal business of piracy. He had been a pirate himself, hunting from the Mediterranean to Ireland for slaves and cargoes for the beys and sultans of the Barbary Coast until he was captured and hanged with sixteen others at Execution Dock at Wapping in 1609. Exactly what he composed is unknown, as the ballad which eventually emerged some time between 1663 and 1674 (The Sailors’ onely Delight: Shewing the brave fight between the George-Aloe, the Sweep-stakes and certain French-men at Sea), and then (as it seems) evolved into our song, is a continuous story of twenty-three verses with no apparent break. However, it does have two distinct strands, the first being the capture of the Sweepstake and the second the defeat of a French ship by the George Aloe. It was collected by Child (no. 285), who tells us that a ship called The Swepstacke belonged to Henry VIII in 1545, and another, The Sweepstakes, to Charles II in 1666."