Who was also a Guardsman during Vietnam:
During the Vietnam War, I was what filmmaker Michael Moore would call a "deserter." Along with President Bush and countless other young men, I joined the National Guard, did my six months of active duty (basic training, etc.) and then returned to my home unit, where I eventually dropped from sight. In the end, just like President Bush, I got an honorable discharge. But unlike President Bush, I have just told the truth about my service. He hasn't.
At least I don't think so. Nothing about Bush during that period -- not his drinking, not his partying -- suggests that he was a consistently conscientious member of the Texas or Alabama Air National Guard. As it happens, there are no records to show that Bush reported for duty during the summer and fall of 1972. Nonetheless, Bush insists he was where he was supposed to be -- "Otherwise I wouldn't have been honorably discharged," Bush told Tim Russert. Please, sir, don't make me laugh.
http://www.washingtonpost.com/wp-dyn/articles/A27178-2004Feb9.html