<P> Prior to 1958 , chief petty officer was the highest enlisted rate in both the U.S. Navy and U.S. Coast Guard . This changed on 20 May 1958 with the passage of Public Law 85 - 422 , the Military Pay Act of 1958 , which established two new enlisted pay grades of E-8 and E-9 in all five branches of the U.S. Armed Forces . In the U.S. Navy and U.S. Coast Guard , the new E-8 pay grade was titled Senior Chief Petty Officer and the new E-9 pay grade as Master Chief Petty Officer , with the first selectees promoting to their respective grades in 1959 and 1960 . </P>
when was the rank of senior and master chief petty officer established
20 May 1958 with the passage of Public Law 85 - 422 , the Military Pay Act of 1958 , which established two new enlisted pay grades of E-8 and E-9 in all five branches of the U.S. Armed Forces