Rear-Admiral of the Blue was a senior rank of the Royal Navy of the United Kingdom, immediately outranked by the rank Rear-Admiral of the White.

In 1864 it was abolished as a promotional rank (pictured adjacent is the command flag for a Rear-Admiral of the Blue).

[3] The Rear-Admiral of the Blue was a senior rank of the Royal Navy of the United Kingdom, immediately outranked by the rank Rear-Admiral of the White (see order of precedence below).

[2] The Navy was divided into three squadrons Red, White and Blue in order of seniority.

Ships of the Royal Navy flew the Ensign that coincided with the squadron of their commanding officer.