The drafting of young men to fight in Vietnam bitterly divided America and its legacy is still haunting the presidential race, writes Michael Hill
The Vietnam War-era draft cut a tornado-like swath through a generation of American men.
"It was a crucible question, regardless of where you came down on the war in Vietnam," Alexander Bloom, a historian at Wheaton College in Massachusetts, says of the draft. "It was a question people who did not want to go to that war had to face - whether to go to Canada, to the resistance, to teach in an inner-city high school, whatever helped you stay out. It was not something you did casually."
Those years have surfaced again with allegations about President Bush's service in the National Guard and heroic tales from Senator John Kerry's combat in Vietnam.
When Mr Bush and Mr Kerry faced the draft, eligibility was determined by complex regulations governing deferments.
"Students got out, certain occupations got out, if you had braces on your teeth you got out," says David Segal, director of the Centre for Research on Military Organisations at the University of Maryland.
"Anything that the military didn't have to deal with, it didn't want to deal with because it had all these other people it could call up," he says, referring to the baby boomers reaching age 18.
That made avoiding the draft something of a high-stakes game. Stay within one or more of the safe havens until you reached age 26 and you were no longer vulnerable. But leave one of those havens and you might find yourself under fire in Vietnam.
The game favoured the affluent and educated, who could go to graduate school, regardless of their genuine academic aspiration; who could find a friendly orthodontist to put on braces, no matter what the state of their teeth was.
Mr Kerry and Mr Bush lost their student deferments when they graduated from Yale - Mr Kerry in 1966, Mr Bush in 1968 - at the height of the war and the draft. In 1966, more than 382,000 were inducted through the draft. That was the biggest call-up of the Vietnam era. The second-largest was in 1968, when 300,000 were inducted.
Mr Kerry, from an influential family and an Ivy League school, was the type who usually found a way around the draft. So his choice to join the navy appears unusual, particularly for someone who had just given a talk to his fellow graduates that was critical of the Vietnam War
But Douglas Brinkley, Mr Kerry's biographer, says signing up was not surprising for the son of a one-time test pilot who spent his career in government service.
Mr Kerry's father "felt you had a real duty to your country, almost to an obsession. John Kerry was raised with that. If you cut to 1965 or '66, his father was totally against the war," says Mr Brinkley, author of Tour of Duty: John Kerry and the Vietnam War. "But there was never a sense that the Kerry boys were going to shirk their duty."
Senator Kerry had other influences - a fascination with the story of John F. Kennedy and his second World War heroics, and a close group of friends at Yale that included the grandson of Gen John J. "Blackjack" Pershing, US commander in Europe in the first World War.
Because he was not drafted, Mr Kerry could choose his service - the navy, where only pilots were seeing much combat - and he could try for officer candidate school, a cinch for a Yale graduate.
One way out of going to Vietnam was the National Guard. "The National Guard was very appealing for those individuals who did not want to go to Vietnam but instead stay home and live life as normal as possible," said John C. McWilliams, a history professor at Penn State.
The problem was that once that became clear, a long line formed to get into the guard. With entrance decisions made on local levels, the guard was open to charges that influence was used to get to the head of the line.
"Clearly, there was some political pull involved," Mr Segal said. "There is story after story of people jumping over others on the waiting list."
The system, he says, resulted in a National Guard that was "virtually lily white and largely middle class or better".
The longer the US was at war, "the more connected you had to be to get into the guard".
Most guard units required six months of active duty, followed by weekend assignments.
The Air National Guard Mr Bush joined required a two-year hitch for flight training. Mr Bush has said that is the reason it had no waiting list.
Mr Segal finds that hard to believe. "In 1968, I don't think there was a National Guard unit in the country that did not have a waiting list. But no one would know that except the people in the unit itself." In 1994, Mr Bush said his reason for joining the National Guard was the standard one. "I was not prepared to shoot my eardrum out with a shotgun to get a deferment. Nor was I willing to go to Canada. So I chose to better myself by learning how to fly aeroplanes."
In more recent interviews, the president has promoted his time in the guard, noting that many guard members are in Iraq.
Many say that if Mr Bush did miss some guard meetings in the waning years of his commitment in the 1970s, he was not alone. With the Vietnam War winding down, the locally-controlled guard units were often lax about such things.
Trying to end the inequities of conscription, the government held the first draft lottery on December 1st, 1969. It would determine the order of call-up in 1970 for everyone born between 1944 and 1950 still eligible for the draft.
When that first lottery was held, Mr Bush was in flight training in Texas. Mr Kerry had been home from Vietnam for a few months. He had served on a ship off shore, but, Mr Brinkley says, in 1968 asked for the command of one of the Swift boats that were doing uneventful Coast Guard duty in Vietnam.
The mission changed a few weeks later, and the Swifts were sent up Vietnamese rivers, essentially to draw enemy fire. Mr Kerry's time in that combat earned him a Silver Star, a Bronze Star and three Purple Hearts, wounds that qualified him for an early trip home, which he took.
The lotteries continued for four more years, but the call-ups diminished. The draft was abolished in 1973, replaced by an all-volunteer army. But decisions made then still cast shadows.
"It continues to go on and on and on, almost 30 years after the fall of Saigon," says historian Bloom. "We are haunted by Vietnam."