Here is a good piece from factcheck.org on Bush and the guard. I quote a few highlights here:
–After graduating from Yale in 1968, Bush escaped conscription and possible combat duty in the then-raging Vietnam War by getting into the Texas Air National Guard. During the next four years Bush served the equivalent of 21 months on active duty, according to the Globe account [which started the whole controversy], including more than a year of flight training. The Globe quoted Bush’s flight instructor, retired Col. Maurice H. Udell, as saying “I would rank him in the top 5 percent of pilots I knew.”
The Globe also said:
Those who trained and flew with Bush . . . said he was among the best pilots in the 111th Fighter-Interceptor Squadron. In the 22-month period between the end of his flight training and his move to Alabama, Bush logged numerous hours of duty, well above the minimum requirements for so-called “weekend warriors.”
–Records are lacking for that period [in Alabama]. However, The Associated Press quoted two friends who worked with Bush in the Blount campaign as saying they recall him attending Air National Guard drills in Alabama. Joe Holcombe, described as a former Republican county chairman in Alabama, was quoted as saying, “It was pretty well-known that he was in the Guard while we worked on the campaign.” And Emily Martin, who said she had dated Bush during the campaign, was quoted saying, “He told us that he was having to do his Guard duty in Alabama while he worked on the campaign.”
– George Magazine reported in October of 2000:
It’s time to set the record straight . . . . Bush may have received favorable treatment to get into the Guard, served irregularly after the spring of 1972 and got an expedited discharge, but he did accumulate the days of service required of him for his ultimate honorable discharge.
The New York Times reported Nov. 3, 2000:
But a review of records by The New York Times indicated that some of those concerns (about Bush’s absence) may be unfounded . . . . A review by The Times showed that after a seven-month gap, he appeared for duty in late November 1972 at least through July 1973.