Then he broke with one of the military's most deeply rooted traditions and vowed to lift the ban on women serving in combat.
And the commander in chief has aggressively sought to change military culture by cracking down on sexual assault and sexual harassment, problems that for years were underreported or overlooked.
Obama is an unpopular president in the eyes of the men and women in uniform. Yet his two-term administration is etching a deep imprint on the culture inside the armed forces. As commander in chief, he will leave behind a legacy that will shape the Pentagon's personnel policies and the social customs of rank-and-file troops for decades to come.
For Obama's supporters, the cultural changes he's overseeing are on a level with President Truman's 1948 order that desegregated the military and put it at the forefront of the national push for racial equality.
But to his critics, his moves amount to heavy-handed social engineering that erode deep-seated traditions and potentially undermine good order and discipline.
And for the troops in today's career force, the wave of changes to deep-seated policies and attitudes can be jarring.
"It's a very different Army than the one I came in to," said Sgt. 1st Class Eric Rexilius, who joined the Army 21 years ago and is now a helicopter repairman at Joint Base Lewis-McChord in Washington state.
"I personally don't think it's a bad change," he said â€" while acknowledging that among his cohort of older career soldiers, "I'm probably a minority."
"For most of my peers," Rexilius said, "it makes them uncomfortable because it's not what they are used to."
The long-term effects of Obama's social policies on the military remain unknown. But one thing is clear: He is a deeper unpopular commander in chief among the troops.
According to a Military Times survey of almost 2,300 active-duty service members, Obama's popularity â€" never high to begin with â€" has crumbled, falling from 35 percent in 2009 to just 15 percent this year, while his disapproval ratings have increased to 55 percent from 40 percent over that time.
But despite their misgivings about him personally, evidence suggests some quiet acceptance, and even support, for his policy changes.
The greatest cultural shift under Obama may well be the swiftly-growing acceptance of homosexuality in the ranks following the official change in law that took effect in September 2011.
A Military Times poll in 2009 found 35 percent of troops felt that gays and lesbians should be allowed to serve in uniform. Five years later, that figure has jumped to 60 percent.
Similarly, open opposition to homosexuality in the military has collapsed. In 2009, 49 percent of troops felt gays, lesbians and bisexuals should not be allowed to serve. In 2014, such disapproval fell to just 19 percent.
It is "the biggest change in the military's culture that happened on [Obama's] watch," said Richard Kohn, professor emeritus of history and peace, war and defense at the University of North Carolina at Chapel Hill.
During years of intense political debate about gays in the military, the military's top brass repeatedly voiced firm opposition and warned that such a sweeping change could create a serious morale crisis. But in the three years since the law changed, military leaders have seen virtually no problems.
"We have heard no reporting of the kinds of disruptions that were predicted," Kohn said. "It has been unsurprisingly smooth. It's not surprising because military people have always known of gay people and lesbians in their units, and have either accepted them, or abused them based on the quality of their leadership. There's been a change of public opinion, and the fact that the force is made up largely of young people," who tend to be more tolerant of homosexuality."
Petty Officer 2nd Class Nate Bates, a Navy hospital corpsman who is gay, said his co-workers essentially shrugged when they found out.
"It was like no big deal: ... 'Oh, OK, I didn't know, but we're still cool,' " he said.
The nonchalant reaction was a tremendous relief to Bates, who came out in January because he was about to marry his husband, Wayne, an Army soldier.
"I was nervous, but it had gotten to the point where, 'I'm getting ready to get married, but I'm not going to hide this person I love,' " Bates said. "I just didn't care what anybody else thinks about it."
And it's provided opportunities to increase understanding, Bates said. He cited one friendship with another sailor whom he didn't think had ever previously had a close friendship with a gay or lesbian person.
Now, "We ask him to hang out, he knows about my husband, he has a girlfriend and is thinking about getting married," Bates said. "He was asking us, 'Have you ever thought about adopting?' It's normal conversations like that."
But not every experience has been so positive.
Bates said his Army husband has encountered hostility from his commanders and fellow soldiers since coming out. He said his husband has heard senior noncommissioned officers use homophobic slurs.
His husband, who is in Kuwait on his fourth deployment overseas, hasn't been picked to go on missions he asked for, he believes because he is gay. And the Bates' request to be co-located as a legally married couple has been approved by the Navy but held up by the Army.
The final straw came in April, Bates said, when he contracted an unknown illness and ended up in an induced coma. His husband asked his supervisors for permission to come home to help care for Nate, but his request was denied. Particularly aggravating, Bates said, was the fact that other soldiers in his husband's unit were allowed to come home for less-urgent events like graduations.
"I was in the hospital seven days, and on convalescent leave another seven days at home," Bates said. "There was nobody by my bedside that whole time. Because of actions like that, he's leaving [the Army] within the next year and a half."
Some gay troops say lingering homophobia in the military still compels them to hide their sexuality while in uniform. And some don't think they'll ever be able to come out of the closet as long as they are in the uniform.
"Nothing's really changed for me" since the don't-ask-don't-tell policy was repealed, said a gay master sergeant in the Air Force who asked to remain anonymous. "I think [coming out] would ruin my career."
The master sergeant said that the end of DADT helped younger troops, who feel more comfortable coming out. But for senior noncommissioned officers, he said, it's a different story.
"For SNCOs, it's word of mouth for promotions," the master sergeant said. "We've still got some crusty old chiefs â€¦ on the promotion board, making decisions. It'll take a few years to get them out."
He said he's heard some Air Force chief master sergeants make derogatory, homophobic comments â€" sometimes including slurs â€" about younger airmen who have come out. And if those chiefs knew he was gay, he said, he could kiss goodbye any chances of making senior master sergeant.
Another major cultural shift under Obama can be seen in the evolving policies on women serving in combat units.
In 2012, the Pentagon set in motion a plan to carefully lift all gender-based restrictions on all military jobs. But the four services have until 2016 to fully end the ban on women in combat units or seek exemptions for specific jobs such as infantry and special operations. It will be at least several years, maybe more, until the full impact of that policy becomes clear.
Yet already the force is slowly coming to accept the change.
From 2011 to 2014, the percentage of survey respondents who felt that all jobs in combat arms units should be opened to women remained unchanged at 24 percent.
But the percentage of troops who felt some combat-arms jobs should be opened up to women â€" while allowing the military to continue to place some jobs off-limits â€" increased from 34 percent to 41 percent, while the percentage of respondents who felt the military should not change its policies excluding women from combat arms units fell from 43 percent in 2011 to 28 percent in 2014.
"I grew up with five sisters, and I know they're as capable as any man," said an Army staff sergeant who asked for his name not be used. He is a CH-47 helicopter mechanic who has deployed to Iraq and Afghanistan multiple times and supports having women in combat-arms units. "Women are in harm's way to start with. It would just change the location of where they're in harm's way."
But others said they see problems â€" both operationally and culturally.
"They didn't realize you didn't need to protect" a female soldier, he said. "The chivalry factor is always there. There's always going to be, out of every 10 guys, five guys who will want to protect her because she's their little sister. There are three guys who are trying to hook up with her, and there are two guys who hate her and treat her like crap because she won't hook up with them."
"For good or for bad, all-male units like the infantry and artillery and tankers, it's like a seventh-grade locker room," the captain said. "Some guys, the maturity isn't there yet."
He said introducing women into previously all-male units also can cause trouble at home.
"Another problem is the wives," he said. "Everybody's OK with an all-male unit until the wives see there's a fit, ambitious young lady, and you're going to go overseas with 15 dudes, and I'm supposed to trust that situation? That creates a lot of stress family-wise. No matter what the soldier may or may not be doing, his spouse might be convicting him either way."
Over time, he believes the military will adjust. But "until it all works itself out, which eventually it will, there's going to be growing pains," the captain said.
Marine 2nd Lt. Christopher Fox, a student naval aviator who was a radio operator during his prior enlistment, believes putting women in combat jobs is just a bad idea.
"There are a lot of accommodations that have to be made where females are present," he said. "It changes the whole dynamic of a unit. I cannot explain to you the drama that centered on females. I had a sergeant that was not only dating one of the females [at his old communications squadron], they were living together. It caused a lot of tension in the shop."
Defense Secretary Chuck Hagel visited female Marines on an infantry training range at Camp Lejeune, North Carolina, in November. Afterward, he spoke to about 200 mostly male Marines and told them this change reflects the nation's history.
Hagel noted that the U.S. is a country "that believes strongly that every individual deserves the same opportunities, if you're capable, if you can qualify, if you can do the job. And we are doing that."
A third cultural shift under Obama is in how the military approaches and deals with the pervasive problem of sexual assault i
n the ranks.
"They've just started to get more successful by establishing programs, getting senior leadership to speak out on it, and enforcing bans," Kohn said. "It's going to take a lot of time and effort, and we're not going to know for a while the extent to which we're successful."
Combatting sexual assault is not only the moral thing to do, Kohn said. As the economy improves and potential recruits have more job opportunities open for them, the military can't afford to be viewed as a place that does not take sexual assault seriously.
"The military knows it needs to attract the best," Kohn said. "And if women aren't going to enlist because they fear assault, it's going to hurt recruiting."
Yet the Military Times survey showed some dissatisfaction with the service's focus on sexual assault. Only about half of respondents believe sexual assault to be a "serious or significant" problem in the military. About 18 percent had no opinion and 31 percent said they they do not believe it's a significant or serious problem.
Nearly all troops said their unit recently conducted some form of sexual assault training, yet only 48 percent said they believed it was effective.
About 31 percent of troops surveyed were "not sure" whether the training was effective, and 21 percent said it was not effective.
And 16 percent â€" about one in every six or seven troops â€" believe sexual assault training is having a negative effect on military culture.
Army Staff Sgt. Alexander VanArsdall said the military's sexual harassment and assault prevention training has been "one-sided," and overly focused on painting men as aggressors and women as victims.
"A common thing among male service members, when they head into the training, is to say, 'It's time to learn what a racist, sexist, intolerant bastard I am,'
Not only does this create a divisive command climate and leave male troops feeling defensive, he said, but it may be backfiring, and result in some troops not putting their training to use when they have an opportunity to intervene and stop a potential sexual assault.
"The more you beat somebody down on something, the more likely they are to say, 'Screw this,' and toss it aside," VanArsdall said. "The less likely they are to be conscious about something â€" check their buddy out, and make sure he's doing the right thing. They get sick of being browbeat over something they're not doing."
He acknowledged that the military has problems with sexual assault and sexual harassment, and that training is needed. But the training has been inadequate in many ways.
"Is there a culture problem in the military? Absolutely," VanArsdall said. "Yes, this is a discussion we need to have, but the military and the Army's approach is wrong."
He noted that sexual assault prevention and response training has almost entirely portrayed sexual assault as a male-on-female crime. The military's classes should also recognize that male-on-male, female-on-female, and â€" although it's rarely acknowledged â€" female-on-male sexual harassment and sexual assault.
VanArsdall also said that after the military began seriously acknowledging its sexual assault problem about two years ago, units began requiring troops to attend multiple, redundant courses. First it was twice-yearly, then quarterly, then monthly, or even more frequently than that, which he also thinks prompted some troops to reject the message.
"We literally were having sexual assault prevention and response classes every single week â€¦ for a good two or three months," VanArsdall said. "It was the exact same training, the exact same words. After a while, people start to tune it out. It was in one ear and out the other, just checking a block."
Things have improved lately, he said. His new unit has one annual block of training, as well as additional quarterly training sessions, which he said seems about right.
And the training classes are starting to become more interactive. He said the sessions used to amount to little more than watching a basic video or PowerPoint powerpoint presentation. Now, he said, the classes feature interactive videos that walk troops through different scenarios, pause along the way, and give troops several options to choose from.
Former Army Sgt. Ralph Demaree, who recently retirerd, thinks the increased focus on sexual assault has created a double standard where accusations against enlisted troops are punished more swiftly than those against officers â€" a phenomenon often described as "different spanks for different ranks."
"If there's an accusation against an enlisted soldier â€¦ everyone beats down on him," Demaree said. "Some form of action will be taken against him before any investigation is completed. If it's an officer, everything's hush-hush."
Demaree said he feels strongly that the military needs to treat all accusations equally.
"Regardless of how high they go up, it needs to be exactly the same, whether it's a private just coming in or a general."
VanArsdall said it's important to have strong, effective sexual assault and prevention training not only for young male troops, but also for young female troops. He said he has intervened in some situations where a female troop didn't recognize she was being harassed or assaulted.
He intervened in one encounter in 2013 during a joint training environment, where a young male Marine on a break began telling a young female sailor that he had a stain in the groin area of his uniform. The male Marine began essentially straddling the female sailor on a bench while she laughed, at which point VanArsdall intervened and told them that wasn't appropriate.
"Her reaction was, 'No big deal, he's just playing,'
Staff writers Andrew Tilghman, Hope Hodge Seck, David Larter and Michelle Tan contributed to this story.
Army Sgt. 1st Class Gregory Pettigrew said before November's midterm election that he felt feels like he should vote, in the midterm elections on Nov. 4, but that he was completely dissatisfied with the ballot options on the ballot.
But he's completely dissatisfied with the options on the ballot.
"I just feel like all politics goes back to money," the 32-year-old soldier said. "It seems like all the [congressional] debate now is completely disconnected from reality. They don't really seem to care about how their decisions impact us."
He's not alone in that opinion. Results of the most recent annual Military Times Poll of more than 2,200 active-duty troops show growing frustration with gridlocked congressional politics, mirroring low approval ratings for national lawmakers in recent polls.
More than one-third of readers who responded to the Military Times Poll said that neither Democrats nor Republicans have been a strong advocate for the military, and 44 percent think both major political parties have become less supportive of military issues in recent years.
Only 12 percent believe both parties have the armed forces' best interests at heart.
That makes rhetoric on pay raises, training policies and budget cuts even more personal for service members like Pettigrew, a 13-year veteran stationed at Fort Sill, Oklahoma.
"Congress is responsible for keeping us at reasonable pay and funding levels so we can do our job," he said. "But from their comments, I don't know if they have any regard for the things we do every day."
One Air Force lieutenant colonel who responded to the poll but did not want to be identified said field combat and medical training exercises have dropped sharply because of funding trims, leading to worries among his airmen about their readiness for future missions.
And a Navy master-at-arms stationed in Europe who also asked to remain anonymous, said his sailors often don't have the spare parts readily available to repair the harbor security vessels they man.
Both blamed congressional infighting for the shortfalls.
The loss of faith in lawmakers comes at a time when troops are less likely to identify with either major political party.
In the last nine years of the Military Times Poll, the percentage of respondents who consider themselves Republican has slowly dropped, from nearly half of those surveyed in the late 2000s to just 32 percent this year. Increasingly, readers are more likely to describe themselves as libertarian (9 percent) or independent (28 percent).
Likewise, readers who described themselves as "very conservative" have remained steady over the years, but "conservative" respondents have dwindled as well â€" down to 29 percent from a high of 41 percent in 2011.
Democrats and liberal readers make up about 8 percent of the poll respondents.
National polls of veterans have shown a strong preference for Republican candidates over Democratic hopefuls, although not as wide a gap as shown in the Military Times Poll. But they have also shown the same strong affinity for the "independent" label, more so than voters without military experience.
Army Maj. Wayne Lacy describes himself as a libertarian but said he has seen some of his fellow soldiers gravitate away from the Republican Party line and toward tea party candidates.
But the 45-year-old staff officer at North American Aerospace Defense Command in Colorado Springs, Colorado, sees that as a subtle shift more than a philosophical change in troops' politics.
"After 25 years, I think it's fair to say most of the force remains fairly conservative in their values," he said.
Feaver concurred, saying he doesn't see "a tidal wave of libertarianism" in the military. Instead, it's a reflection of the same political frustration nationwide, indicated in a recent Gallup Poll that had fewer than one in five Americans approving of Congress' job performance.
Politics as usual
When the new Congress is seated in January, lawmakers will immediately face a host of military issues: sequestration, Islamic militants in Iraq and Syria, lingering Veterans Affairs Department access problems, military pay and retirement reform.
All are issues that the current Congress has struggled to deal with, despite repeated promises of supporting the troops and keeping the nation secure.
Marine Lt. Col. Amy McGrath, a political science instructor at the Naval Academy, said she thinks the political infighting doesn't affect most troops' ability to do their jobs, but it does weigh on their minds, especially those of her students.
"They don't have a framework of reference because they haven't seen it yet," she said. "I spent a year on Capitol Hill as a congressional fellow. ... The fact that they can't come together, it's all politics. It's not one side wanting to cut."
Pettigrew said the October 2013 government shutdown and preceding shutdown threats caused major concern among his fellow soldiers, especially amid rampant rumors of paycheck delays. That only increased his dissatisfaction with the state of national politics.
President Obama gets similar low support from Military Times Poll respondents, with 55 percent disapproving of his performance as commander in chief.
Even support for the tea party was spotty, with just 13 percent of readers saying they back nearly all tea party candidates and 34 percent saying they never back the conservative offshoot.
Despite mixed feelings about national candidates, military voters in recent years have been more engaged than their civilian peers. According to statistics from the Federal Voting Assistance Program, the number of troops voting in recent presidential elections has stayed around 55 percent, just below national rates, and around 45 percent in midterm elections, about 8 percentage points above civilian rates.
Despite his misgivings, Pettigrew said before the midterm election that he probably would will be one of those participating military voters.
"I don't particularly like my choices," the self-proclaimed independent voter said. "But I still really need to vote."
Staff writers Andrew Tilghman, Hope Hodge Seck, David Larter and Stephen Losey contributed to this report.
Those are among the key conclusions of our special report on America's military, "A force adrift: How the nation is failing its troops and veterans." This series was built upon an exclusive survey of almost 2,300 active-duty troops. Included are firsthand accounts from soldiers, sailors, airmen and Marines on how they're coping with a relentless operational tempo, deep cuts in end strength, a growing workload and shrinking compensation.
The series reflects a stunning reversal of fortune for troops who only a few years ago were regularly rewarded with big pay raises, new benefits and well-deserved public adulation for their service.
Yet for all the flag waving and political grandstanding while the wars in Iraq and Afghanistan raged at full tilt, this latest postwar period seems to be bringing an awkward and uncomfortable reprise to the fore.
As in past post-war periods, the troops now are being regarded as a budgetary burden rather than the national security backbone that must be continuously maintained at robust levels of manpower, training, readiness and compensation. Time and again, the nation has had to endure the painful lesson that it is far more costly, and dangerous, to adopt a "boom and bust" model in which the military is allowed to degrade between conflicts.
The morale crisis revealed by Military Times' survey sounds a warning that we are seeing this scenario yet again, as lawmakers and the nation renege on their wartime vows of support for the 1 percent of our citizenry who volunteer to serve in uniform.
McCain, likely to lead the Senate Armed Services Committee in the new Republican-controlled Congress, said the situation "requires immediate attention and action" by the White House, Pentagon and Congress.
In the near term, two festering issues loom if Pentagon leaders hope to thwart a worsening internal crisis: the legacy of the wars in Iraq and Afghanistan, and the future of military compensation.
Military Times' survey indicates top officials will find it a big challenge to address the enormous cynicism and pessimism among troops about the wars in which they were asked to sweat and bleed for more than a decade.
The percentage of troops who feel the war in Afghanistan ultimately will be viewed as a success has taken a nosedive since 2007. Similarly, only 30 percent of respondents feel the eight-year Iraq War was a success. And when we asked whether the U.S. should send a large force of combat troops back to Iraq to fight Islamic State militants, 70 percent of survey respondents said no.
The pessimism about Iraq is especially understandable; troops have spent years listening to senior leaders tell them Iraq was emerging as a stable democracy, its army a reliable ally in the fight against Islamic extremism. Just a few years later, both notions turned out to be spectacularly wrong.
"The junior folks have a right to question their leaders and say, 'Hey, you told me to do this U.S.-led counterinsurgency, and it didn't work. What the heck?' They want to know why they were told to do all the dumb stuff they were told do," said retired Army Lt. Gen. Daniel Bolger, who commanded troops in both Iraq and Afghanistan â€" and who took a stab at addressing those questions in his controversial new book titled "Why We Lost."
In February, more earthquakes may come with the arrival of the final report and recommendations from the Military Compensation and Retirement Modernization Commission.
The last time the Pentagon and Congress allowed the value of military compensation to erode significantly, troops responded with their feet, creating a major recruiting and retention crisis in the late 1990s that took years to reverse.
In this latest postwar era â€" even as new threats spark around the world â€" the nation simply cannot afford to watch its military get taken over that cliff again. And with all that's asked of it, America's military certainly deserves better.
About 70,000 subscribers received e-mail invitations to participate. Others were recruited via social media. In total, about 10,000 respondents completed the survey, including 2,299 who identified themselves as current active-duty personnel.
The sample is not a perfect representation of the military as a whole; it over-represents soldiers, officers and noncommissioned officers, and under-represents junior enlisted personnel. However, it is representative of the more senior and career-oriented members of the force who run the military's day-to-day operations and carry out its policies.
After the survey's completion, Military Times reporters spent several months interviewing dozens of active-duty survey respondents, speaking with them in detail about their views on military life today. In some instances, service members asked not to be identified so they could speak more candidly about military policy, senior leaders and political views.
Military Times has conducted a similar survey routinely for the past 10 years. Survey data cited from years prior to 2014 are based on those survey results. This is the only long-term, independent tracking survey of its kind.
The voluntary nature of the survey, the dependence on e-mail and the characteristics of Military Times readers may affect the results. Statistical margins of error commonly reported in opinion surveys that use random sampling can't be calculated for this survey.
Readers or researchers with questions about the methodology and analysis may contact staff writer Andrew Tilghman at firstname.lastname@example.org.