How the Royal Navy's colored flag ranks worked

Rear admirals progressed through blue, white, and red grades, followed by the same sequence for vice admirals and admirals. The colours came from fleet squadrons: white in the van, red in the centre, and blue at the rear. A commodore was a captain given an appointment for a particular command rather than another permanent step in that sequence. Colour grades let the navy establish relative authority without immediately promoting an officer to the next broad rank. A rear admiral of the red could therefore command a rear admiral of the blue. The so-called yellow squadron provided admiral status for officers who were not expected to receive active employment, while the Admiralty also had ways to avoid promoting every unsuitable senior captain.