The Sikhs of northwestern India have for centuries cherished their rich military history. Wearing long beards and turbans into combat, they have battled Mughals in Punjab, Afghans near the Khyber Pass and Germans in the bloody trenches of the Somme.

But when Maj. Kamaljeet Singh Kalsi, an American Sikh raised in New Jersey, signed up for the U.S. Army, that tradition counted for nothing. Before sending him to officer basic training, the Army told him that he would have to give up the basic symbols of his religion: his beard, knee-length hair and turban.

In good Sikh tradition, he resisted. Armed with petitions and congressional letters, he waged a two-year campaign that in 2009 resulted in the Army granting him a special exception for his unshorn hair, the first such accommodation to a policy established in the 1980s.

Since then, two other Sikhs have won accommodations from the Army. But many others have failed. And so now, as he prepares to leave active duty, Kalsi, who earned a Bronze Star in Afghanistan, is waging a new campaign: to rescind those strict rules that he believes have blocked hundreds of Sikhs from joining the military.

"Folks say, ‘If you really want to serve, why don’t you cut your beard?’" said Kalsi, a doctor who is medical director of emergency medical services at Fort Bragg in North Carolina. "But asking a person to choose between religion and country, that’s not who we are as a nation. We’re better than that. We can be Sikhs and soldiers at the same time."

At stake for the military is the uniformity in appearance that it deems necessary for good order and discipline. "A neat and well-groomed appearance is fundamental to Army service," said Troy A. Rolan, an Army spokesman. "It is an outward symbol of a disciplined military."

But to Sikh advocates and their supporters in Congress, the policies governing appearance are as fundamentally discriminatory to them as racially segregated units were to blacks, combat prohibitions were to women and the "don’t ask, don’t tell" policy was to gay men and lesbians.

"They love this country," said Rep. Joseph Crowley, D-N.Y., who has been urging the Pentagon to change its rules regarding Sikhs. "If they want to serve, we should let them do it."

Sikh leaders cite an additional reason for their push. In the days after the Sept. 11 attacks, Sikhs were attacked, and at least one was killed, by assailants who confused them with fundamentalist Muslims. Last year, a white supremacist shot to death six Sikhs in their gurudwara, or place of worship, near Milwaukee.

The more Sikhs wear military, police or firefighter uniforms, Kalsi reasoned, the less often Americans will see them as threatening outsiders. "When you see a Sikh firefighter save your daughter, you’ll think, ‘That’s a member of my community,’" said Kalsi, a 36-year-old father of two.

Although there were Sikhs in the United States in the 19th century, their population grew rapidly in the 1980s after a crackdown against an independence movement in Punjab caused thousands of Sikhs to emigrate. Today the Sikh Coalition, an advocacy group, estimates that about half a million Sikhs live in America. There are about 30 million Sikhs worldwide.

The first Sikh guru was born a Hindu in the 15th century, but the monotheistic religion he founded was more democratic than Hinduism, rejecting caste and embracing worshipers of both genders and all races.

As the religion took root in what is today northwestern India, Sikhs formed their own militias to defend against marauding armies. When the British colonized the region, they recognized that fighting spirit and created Sikh battalions to carry the empire’s banner across the globe. Today, Sikhs continue to serve in the Indian military in numbers far exceeding their small portion of the population.

Nikky-Guninder Kaur Singh, the chairwoman of the department of religious studies at Colby College in Maine, said the five articles of Sikh faith were established by the 10th Sikh guru to give his people a sense of identity when they were chafing under the Islamic Mughal court of Delhi.

The five articles are unshorn hair, a comb, a wristband made of iron or steel, underwear (a symbol of sexual modesty and personal hygiene) and a sword. The turban is worn as a sign of religious respect but also as a matter of practicality, to bind up long hair.

"To challenge that oppression, guru said, ‘Be who you are: Hold your sword, wear your hair long,’" Singh said. "It was partly to instill courage."

Until 1974, Sikhs were allowed to serve in the United States military with unshorn hair and beards. But in the 1980s, stricter rules regarding personal appearance were enacted. Sikhs on active duty at that time were allowed to keep their articles of faith, but future recruits were required to seek case-by-case exceptions. No one succeeded until Kalsi in 2009.

Petitioning can be time-consuming and difficult. And because accommodations are based partly on military necessity, recruits without special skills like being doctors or speaking foreign languages can easily be rejected. Moreover, exceptions are viewed as temporary, meaning Sikh soldiers can be ordered to cut their hair and shave their beards at any time.

Among the concerns raised by the armed services – all branches have rules similar to the Army, according to the Sikh Coalition – is whether Sikh men can safely wear helmets and gas masks.

But Kalsi, who spent seven months in Afghanistan in 2011 running a field hospital in Helmand province, said he routinely wore a helmet over his long hair, which he bound under a special wrap. He noted that the Israeli military, as well as bearded American Special Operations troops, had proved that gas masks worked fine over thick beards.

Kalsi has even created his own military turbans, which bear his rank insignia and are made from the same camouflage material used in Army combat uniforms.

A more nuanced challenge for Sikh recruits is overcoming the military’s argument that uniformity of appearance is essential for "unit cohesion," the military’s shared sense of purpose and tradition. But Sikhs point to the British, Canadian and Indian militaries, where Sikhs are allowed to wear unshorn hair and beards, as evidence that their articles of faith do not undermine esprit de corps.

Spc. Simranpreet Lamba, a 29-year-old Army medic based at Joint Base Lewis-McChord in Washington state, said he had dreamed of joining the military as a child in India. After he immigrated to the United States in 2006, he decided to enlist after Kalsi received his exception. The Army granted him an accommodation under a program for immigrants with foreign language skills.

Though Lamba said he sometimes got quizzical looks on bases, his commanders and unit mates had been very welcoming. Scheduled to become a sergeant this year, he is thinking about trying to become a commissioned officer.

"My brigade is so used to me, they don’t look at me as someone who is different," he said.

For Harmandeep S. Grover, a 24-year-old immigrant, joining the Army is very much about becoming an American.

Working as a United Parcel Service driver while attending college in Washington, he repeatedly had customers call the police when he delivered packages. He printed up T-shirts with a response: "I am a Sikh. Google it."

He was recently accepted into the same language-skills program that Lamba used to enlist. Now he must wait for the Army to consider his request for an accommodation.

"I want to be part of this country," he said.

© 2013 The New York Times Company