Entering through the main gate? Not very bright. In the 60s-70s mexican groups trying to steal arms and peace protestors tried to and sometimes gained entry by way of some remote access points. Pendleton is a vast area with remote ranges and training areas. There was a story (maybe urban legend) that some peaceniks made their way into a remote area of the base at night but fortunately for them were spotted by an artillery observer near the impact area where a live fire artillery night training exercise was taking place.
Could go either way; for a short time in 1967 I was attached to an artillery battery that was indeed way out in the boondocks there; most artillery exercises took place at 29 Palms, though - at that time it was stricty an artillery base.
A distraction. Where were the others at the time? What was the left hand doing?