actually Bubba issued orders as Commander In Chief that military bases at home and abroud should "de-militarize", reducing the number and visibility of their armed guards. it was part of his Kinder and Gentler military proram
but the policy establishing that off duty personnel are prohibited form carrying arms except under orders is long established.
when billeted, every man was generally ordered to Pile Arms, and those arms were stored in an armoury. except for those doing Duty Under Arms, the rest of the personnel have been disarmed for nearly the entire history of military firearms.
unless the threat of attack is imminent, or theres actual shootin goin on, "Rear Positions" are pretty much disarmed all the time, and have been since the revolution.
the prohibitions on possessing loaded arms in encampment even required that the First Sergeant personally worm the ball of each musket as a guard shift retired, and send the powder and ball to the quartermaster.
http://lcweb2.loc.gov/cgi-bin/ampage?collId=rbc3&fileName=rbc0001_2006batch30726page.db&recNum=127