I have often heard said that the nine U.S. 5-star military and naval
officers of the WWII era never retired, that is, that they remained on
active duty at full pay until their deaths. Is this true and, if so,
under what Federal statute is such entitlement provided? Related
question: during Desert Storm it was rumored that Pres Bush the elder
had contemplated awarding Gen Colin Powell a fifth star. Had he
decided to do so, would an act of Congress have been required or would
the president simply have invoked a statute then and currently in
force?

Interesting questions, nautico-ga.  
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Disregard my questions, as I found adequate answers on the following site:

http://www.hazegray.org/faq/smn3.htm#C6