where does the term petty officer come from
Petty officer The modern petty officer dates back to the Age of Sail. Petty officers rank between naval officers (both commissioned and warrant) and most enlisted sailors. These were men with some claim to officer rank, sufficient to distinguish them from ordinary ratings, without raising them so high as the sea officers. Several were warrant officers, in the literal sense of being appointed by warrant, and like the warrant sea officers, their superiors, they were usually among the specialists of the ship's company.[1] The Oxford English Dictionary suggests that the title derives from the Anglo-Norman and Middle French "petit", meaning "of small size, small, little".[2]
Commander (United States) In the United States Navy, the United States Coast Guard, the United States Public Health Service Commissioned Corps, and the National Oceanic and Atmospheric Administration Commissioned Officer Corps, commander (abbreviated "CDR") is a mid-grade officer rank, with the pay grade of O-5. Commander ranks above lieutenant commander (O-4) and below captain (O-6). Commander is equivalent to the rank of lieutenant colonel in the other uniformed services.[2] Notably, it is the first rank at which the holder wears an embellished cap, whereas officers of the other services are entitled to embellishment at O-4 rank. Promotion to commander in the US Navy is governed by Department of Defense policies derived from the Defense Officer Personnel Management Act (DOPMA) of 1980 or its companion Reserve Officer Personnel Management Act (ROPMA). DOPMA/ROPMA guidelines suggest that 70% of lieutenant commanders should be promoted to commander after serving a minimum of three years at their present rank and after attaining 15-17 years of cumulative commissioned service, although this percentage may vary and be appreciably less for certain officer designators (i.e., primary "specialties") dependent on defense budgets, force structure and needs of the service.