E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
corruption of Amir-al. Milton, speaking of Satan, says:
His spear (to equal which the tallest pine
Hewn on Norwegian hills, to be the mast
Of some tall amiral, were but a wand)
He walked with.Paradise Lost, i. 292.
The word was introduced by the Turks or Genoese in the twelfth century, and is the Arabic Amir with the article al (lord or commander); as Amir-al-ma (commander of the water), Amir-al-Omra (commander of the forces), Amir-al-Mminim (commander of the faithful).
English admirals used to be of three classes, according to the colour of their flag
Admiral of the Red, used to hold the centre in an engagement.
Admiral of the White, used to hold the van.
Admiral of the Blue, used to hold the rear.
The distinction was abolished in 1864; now all admirals carry the white flag.