* Mormon service in U.S. military dates to Mexican-American War
* Church counts war heroes, top generals among its members
* Obama, Clinton also did not serve in armed forces
By David Alexander and Jennifer Dobner
WASHINGTON/SALT LAKE CITY, Nov 3 (Reuters) - While neither of the candidates in next week's U.S. presidential election was in the military, Mitt Romney's age - he was eligible to serve in Vietnam - has raised questions during the campaign about why he didn't serve and whether his Mormon faith had anything to do with it.
Guy Hicks, a Mormon and former officer in the Army Reserve Special Forces, said there is a public misperception that members of the Mormon Church do not serve in the military.
"There is a sense in our culture and in our religious belief that we have an obligation to serve our country, and that's found in military service; it's also found in public service," said Hicks, a senior vice president at aerospace and defense firm EADS North America.
The participation of Mormons in the armed forces is roughly equivalent to their proportion of the population; senior figures in the Church served during World War II; and at least 10 Mormons have won the Medal of Honor.
According to Pentagon records, nearly 18,200 military service members identified themselves as belonging to the Mormon Church as of March, about 1.3 percent of the nearly 1.4 million active-duty personnel. Around 2 percent of the U.S. population identify as Mormons.
Romney was a 19-year-old student at Stanford University in the spring of 1966 when opponents of the military draft occupied a campus building. The Church of Jesus Christ of Latter-day Saints (the formal name of the Mormon Church) was a strong supporter of the Vietnam War, and the clean-cut young Romney protested against the protesters. Photographs show him carrying a placard saying: "Speak Out, Don't Sit In."
Rather than joining the armed forces, however, Romney later that summer chose another path. He obtained a deferment allowing him to avoid military service and traveled to France to work as a missionary for his Church, a traditional form of service for young Mormons. Romney's five sons all followed in his footsteps, serving as missionaries but not soldiers.
Military service used to be a crucial element of a presidential resume, adding gravitas to the person applying for the job of commander-in-chief. But in recent years it has become less of a requirement, and neither Obama nor Bill Clinton served.
In the last election , Barack Obama, who is 51, faced an opponent who was a Vietnam War hero, Senator John McCain, and his predecessor as president, George W. Bush, served in the Texas Air National Guard.
Mormon Church members say the decision to enter the military, government or some other form of service is a personal one. Those who do serve as missionaries are considered officials of the Church, which qualified them for a draft exemption.
"During the Korean conflict and Vietnam War, the Church voluntarily placed restrictions on the number of missionaries sent out from each ward. A bishop could recommend one young man every six months for missionary service," said Mormon Church spokesman Eric Hawkins. "Young men who had received induction notices or whose draft number was likely to be called were not recommended for missionary service."
Romney was prepared to serve in the military after his student deferments expired in the early 1970s, but he wasn't called, his campaign said. "His career choices did not take him into the military, but he has deep respect for all who have served," a spokesperson said.
BOYS TO MEN
Although Romney, 65, is not a veteran and is running against an incumbent whose administration tracked down and killed Osama bin Laden, he heads into Election Day on Nov. 6 with strong support among the military and veterans.
Polling by Reuters/Ipsos during October found that active-duty military personnel and their families support Romney over President Obama by 49 percent to 43 percent. When military veterans and their families are included, Romney led the president 53 percent to 38 percent.
Romney's wife, Ann, told television interviewers recently that the decision by her husband and sons not to serve in the military was unrelated to their religious beliefs. Both Church missionary work and military service help young people to grow and mature, she said.
"My boys did all serve missions, and they went away for two years," she said on the television program 'The View.' "I sent them away boys and they came back men ... and I think this is where military service is so extraordinary, too, where ... you are working and helping others. And that changes you."
She noted, however, that those who serve in the military deserve particular respect for putting their lives on the line.
The Church of Jesus Christ of Latter-day Saints boasts plenty of former servicemen.
Church President Thomas Monson joined the U.S. Navy as a teenager in the closing months of the Second World War. Boyd Packer, president of the Quorum of the Twelve Apostles, a Church governing body, was a bomber pilot in the Pacific.
Other senior Mormon leaders also have served in the military, including retired four-star General Bruce Carlson, who was head of the Air Force Materiel Command before retiring in 2008. He now is a member of the Second Quorum of the Seventy, another Church body.
The Mormon tradition of U.S. military service dates back to the Church's early history following its founding by Joseph Smith and other leaders in 1830.
When war broke out between the United States and Mexico in 1846, President James Polk asked Church leaders to raise a Mormon battalion of some 500 troops, agreeing in exchange to support the Mormons' move to the Salt Lake area. The Mormon battalion marched from Iowa to Southern California, where it performed occupation and border duties until it was disbanded in mid-1947. It never engaged Mexican forces in battle.
Relations between the Church and the U.S. government were tense in succeeding years. A Church-backed militia known as the Nauvoo Legion nearly came to blows with a U.S. military force sent to Utah Territory because of reports of a Mormon rebellion.
The Church abandoned controversial religious practices such as polygamy under pressure from the government in the latter part of the century, and Utah became a state in 1896. Since then, Mormons have consistently served in the military and fought in America's wars.
In modern times, Church leaders have touted the United States as "God's country" and believe that its existence fulfills a prophetic destiny, said Patrick Mason, an associate professor who holds a chair in Mormon studies at Claremont Graduate University in California.
"Serving America is only half a step removed from serving God," he said. Mormon solders in Vietnam were basically told "you're doing God's work here strapping on your M-16 - just like Mitt Romney is doing God's work strapping on his Book of Mormon every day," Mason added.