Commodore (Royal Navy) Commodore (Royal Navy) Commodore (Cdre) is a rank of the Royal Navy above captain and below rear admiral. It has a NATO ranking code of OF-6. The rank is equivalent to brigadier in the British Army and Royal Marines and to air commodore in the Royal Air Force. The rank of commodore was introduced during the 17th century in November 1674 (though not legally established until 1806). In 1684 the navy introduced two classes of commodore, the first known as a "Commodore Distinction" and the other a "Commodore Ordinary"; these would later evolve into commodores first and second class. In
History of the Royal Navy the Royal Scots Navy, taking charge of HMS "Royal Mary" on the North Sea patrol, moving to "Royal William" when she entered service in 1705, and being promoted to commodore in 1706. With the Act of Union in 1707, the Royal Scottish Navy was merged with the English Royal Navy, but there were already much larger English ships called "Royal William" and "Mary", so the Scottish frigates were renamed and , while only retained its name. After 1603 the English and Scottish fleets were organized together under James I but the efficiency of the Navy declined gradually, while corruption grew