There were then nine ranks of admirals carrying the three ensigns:
| Admiral of the White | White ensign. |
| Vice-Admiralof the White | White ensign. |
| Rear-Admiral of the White | White ensign. |
| Admiral of the Red | Red ensign. |
| Vice-Admiralof the Red | Red ensign. |
| Rear-Admiral of the Red | Red ensign. |
| Admiral of the Blue | Blue ensign. |
| Vice-Admiralof the Blue | Blue ensign. |
| Rear-Admiral of the Blue | Blue ensign. |
As merchant ships, which were all flying the red ensign, increased in size, it became increasingly difficult for foreigners to distinguish these from the ships of the Royal Navy—a difficulty which was further intensified for them by the fact that a squadron of the Royal Navy might be sailing on one coast under the blue ensign, while another squadron was sailing under the red, and yet another under the white, according to the rank of the admirals of their respective squadrons.
Confusion and possibility of mistakes in identification in action was sometimes caused by the ships of one squadron becoming intermingled with those of another. Nelson solved this difficulty by directing that only the white ensign, which was the ensign of his own squadron,[182] should be used on the ships of all the squadrons at the battle of Trafalgar.
The three ensigns, with their successive one, two and three-crossed Jacks, had continued to be used in these varying ways during more than two hundred years, until 1865, when the positions of the three ensigns were separated and distinctive duties allotted to each.[183] The number of the rank of admirals was at the same time reduced to three—admiral, vice-admiral and rear-admiral. All of these were to fly, as they still do, the white ensign at the stern, their seniority being indicated by the position of the St. George Jack at the mast head.[184] These ranks are in addition to the rank of Admiral of the fleet, which confers the right to wear the Union Jack instead of the St. George.
The ensigns were described in the Order and directed to be used as follows:
The White Ensign (Pl. [VIII.], fig. 2).—A white flag, with a St. George cross through the whole flag and the Union Jack in the upper canton, to be used at sea only by ships of the Royal Navy or by yacht clubs to which special license has been given.
The Blue Ensign (Pl. [VIII.], fig. 3).—A blue flag, with the Union Jack in the upper canton, to be used only by ships of the Royal Naval Reserve, or by merchantmen which are commanded by officers of the reserve, and have been duly licensed, or by yacht clubs to which special commission has been granted.
The Red Ensign (Pl. [VIII.], fig. 1).—A red flag, with a Union Jack in the upper canton, to be used as a national ensign by all British merchantmen.