1799: Destruction of the English Fleet

1799 is when the image was published, that is my understanding. Anyways, the Google Translated description to the image sounds like this.
  • Fire of the English fleet: the English fleet burned down by the Greek fire and that of the new floating towers, armed with mouths to protect on the coasts the descent of the French at low tide, the favorable winds direct thousands by themselves balloons that ignite at a combined height rain down on English ships.
  • Zoomable Gallica Version
Apparently we still are not sure of the composition of the Greek Fire. It also sounds like the secrets of the Greek Fire were supposed to be lost many many years prior to the below pictured event.

Two questions of mine:
  • When did France have a flag like the one we can see on the floating tower below?
  • What battle is this, and when did it take place?