Republican presidential candidate and business mogul Donald Trump is on the offense, slamming his 2016 competition — Republicans and Democrats alike. Here's what he has to say about his rivals. (Julie Percha/The Washington Post)

A few weeks after his 22nd birthday, Donald Trump received a notice from the federal government. On July 9, 1968, his local draft board had scrawled a “1A” beside his name in its handwritten ledger, classifying him as available for unrestricted military service.

For the previous four years, Trump had avoided the draft — and the possibility of being sent to fight in the Vietnam War — by obtaining four separate deferments so he could study at Fordham University and the University of Pennsylvania. With his diploma in hand and his college days over, he was suddenly vulnerable to conscription.

Trump’s exposure to the draft, however, didn’t last long. Two months later, on Sept. 17, 1968, he reported for an armed forces physical examination and was medically disqualified, according to the ledger from his local Selective Service System draft board in Jamaica, N.Y., now in the custody of the National Archives.

The ledger does not detail why Trump failed the exam — the Selective Service destroyed all medical records and individual files after the draft ended in 1973 and the military converted to an all-volunteer force.

In recent days, Trump, a Republican presidential candidate, and his campaign have said that he received the medical deferment because he had bone spurs in his feet. But rather than clear up all questions about why he did not serve in the military during the Vietnam era, they have given shifting accounts that are at odds with the few remaining documents in his Selective Service file.

Republican presidential candidate Donald Trump said Sen. John McCain (R-Ariz.), a decorated Vietnam war veteran, was not a war hero because he was captured by the North Vietnamese. (C-SPAN)

Trump has given limited information about the nature of his medical ailment from 1968 that left him classified as “1-Y,” or unqualified for duty except in the case of a national emergency.

On Saturday, during a campaign stop in Iowa, Trump said he had a bone spur in his foot but couldn’t recall which one.

Pressed for details, he told reporters to research his draft records. “You’ll have to look it up,” he said. Later that day, his campaign issued a statement saying he had bone spurs in both of his heels.

Trump’s draft board records show that he had another armed forces physical two years earlier, on Dec. 15, 1966. Although the ledger does not spell out the results, he was not granted a medical deferment at the time — indicating that he was found fit for duty.

When Trump registered for the draft at 18 in 1964, he had just graduated as a decorated cadet from the New York Military Academy in Cornwall, where he played football and basketball.

His draft registration card lists him as being 6 feet 2 inches tall, weighing 180 pounds and having birthmarks on both heels. Almost immediately, as he enrolled at Fordham, he was granted the first of his four education deferments.

A new Washington Post-ABC News poll shows businessman and 2016 presidential candidate Donald Trump leading the GOP field for Republican voters. (The Washington Post)

In 1968, Trump obtained his medical deferment at a time when the Vietnam War was intensifying and the military needed a wave of new conscripts.

To help meet the demand, a national draft lottery was held in December 1969, for the first time since World War II. Men born between 1946 and 1950 were assigned a draft number — based on the order in which their birthdates were pulled randomly out of a jar.

Trump, who was born in 1946, and his campaign have given conflicting explanations about how he came to be protected from the draft that year.

In some interviews, Trump has cited his medical deferment and the bone spurs in his feet. But his campaign has given a different reason, saying that he simply lucked out in the 1969 lottery.

That year, young men with the same birthdate as Trump — June 14 — were assigned draft number 356 out of 366, almost last. Anyone with that number was almost guaranteed to avoid being drafted, unless the entire country mobilized.

“When the draft occurred, they never got near his number and he was therefore exempt from serving [in the] military,” Trump’s campaign said in its Saturday statement. “Although he was not a fan of the Vietnam War, yet another disaster for our country, had his draft number been selected he would have proudly served and he is tremendously grateful to all those who did.”

The campaign statement described the medical deferment as “minor” and only “expected to be short-term,” suggesting that it did not shield him from the 1969 draft lottery.

But Trump’s Selective Service record indicates otherwise. The draft board ledger states that his medical deferment remained in place from 1968 until 1972, when it was changed to a similar classification: 4-F, or not qualified for service.

On Tuesday, Trump spokeswoman Hope Hicks did not respond to written questions from The Washington Post about the discrepancy and declined to comment beyond the statement that the campaign had released three days earlier.

Trump was not affected by national draft lotteries that were held in subsequent years; he kept the high draft number he was originally assigned in 1969, as well as his medical deferment.