Gen. Lloyd Austin III, commander of U.S. Central Command, prepares to testify about the Islamic State before the Senate Armed Services Committee last September. (Chip Somodevilla/Getty Images)

In 2011, Gen. Lloyd Austin III, commander of U.S. forces in Iraq, had a simple message about his proposal to keep a residual force of up to 24,000 U.S. troops there: “I want to get this right,” he told his staff, so the next generation of U.S. soldiers doesn’t end up back here.

Two-and-a-half years later, in the summer of 2014, U.S. troops were fanning out across Iraq as the Obama administration scrambled to help a weakened Iraqi government stave off a powerful Islamic State assault.

Austin, from his perch at U.S. Central Command headquarters in Tampa, now oversees an expanding operation against the extremist group, including a force of 3,600 U.S. troops in Iraq, some of whom are taking part in combat operations.

In neighboring Syria, U.S. Special Operations forces are advising local forces in an increasingly complex civil war.

As he prepares to step down this month, the uncertain future of the Iraq and Syria conflicts will weigh on Austin’s legacy, as will sharply deteriorating security in Afghanistan and a grinding insurgent war in Yemen — all part of a command that stretches from Egypt to Pakistan.

An experienced infantryman, Austin was selected to head the most powerful U.S. combatant command in 2013, in part for his deft handling of the Iraq exit, despite his recommendations against a full withdrawal.

The reserved, intensely private Austin was seen as an alternative to high-profile generals, such as Stanley McChrystal or David Petraeus, who created friction inside the Obama administration by publicly airing their views, which often differed from those of civilian leaders.

But it is Austin’s discipline in quietly working within parameters set by the White House that makes his tenure so difficult to evaluate and, critics argue, may have contributed to an overly timid response to the Islamic State.

Peter Feaver, who teaches political science at Duke University, said commanders such as Austin should be judged by the outcome of the wars they lead and by their willingness to provide candid advice.

Austin’s counsel appears to have closely tracked the reticence of senior leaders, including President Obama, to dive back into the Middle East.

Obama “has the military strategy he has chosen, and would choose regardless of who his commander is,” he said. “These are Obama’s strategies more than they are Austin’s.”

A former senior Pentagon official, who like others spoke on the condition of anonymity to discuss a prominent general, said Austin’s cautious approach was a result, in part, of working for a president “who didn’t want to open up a third war” in the Middle East. “His thinking was certainly in keeping with his superiors,” the official said.

A soldier’s soldier

When the towering Austin, a Georgia native, landed at West Point in the early 1970s, he planned to stay in the military for a few years and then become a lawyer. But as he made his way up the ranks, he earned a reputation as someone people wanted to follow into battle and found himself suited to the military life.

As he prepares to retire, Austin’s career has set precedents: He was the first African American officer to command an Army division and corps in combat and the first African American leader of U.S. Central Command.

Speaking in an interview, Austin credited Centcom for coping with the challenges “that have been thrown up here and there” since he became commander.

In Austin’s view, social factors such as sectarian tensions and marginalized youths have driven much of the turmoil gripping the region, including the rise of the Islamic State.

“Unless the leadership in each of these countries is doing the right things, you’re going to have blips on the screen here, and some of these blips are going to be big blips, bigger than blips,” he said.

By early 2014, Austin, then in Tampa, was among a handful of senior U.S. officials closely tracking al-Qaeda in Iraq’s reinvention in neighboring Syria. In June, the group, now called the Islamic State, swept across northern Iraq and captured the city of Mosul.

In the White House discussions that followed, it was clear Obama and top aides wanted to limit involvement in efforts against the group. Obama had campaigned on getting out of President George W. Bush’s insurgent wars. His top military adviser, Gen. Martin Dempsey, was skeptical of the U.S. military’s power to effect change in the region. Galled at the collapse the U.S.-trained Iraqi army, senior officials wanted to avoid U.S. casualties at all costs.

Retired Maj. Gen. Dana Pittard, who was a senior commander in Iraq in 2014, said Austin was “between a rock and a hard place” during that uncertain period as he juggled the imminent militant threat with misgivings in Washington.

“When I would send him things [saying], ‘We’ve got to strike Syria,’ he would calmly say, ‘We’re not authorized to do that,’ ” Pittard said.

When it seemed like the Islamic State might overrun the Iraqi city of Irbil, Austin secured support from Washington for conducting air attacks to protect the city, Pittard said. “It was late Baghdad time. He called, got authority, and within a couple hours, he called back and said, ‘Execute,’ ” Pittard said. “That was my best day there.”

Susan E. Rice, Obama’s national security adviser, praised Austin in a statement. “There is no more complex or challenging set of issues in the world than those he faced, and Gen. Austin led the military effort . . . in a concerted and, more importantly, effective way.”

But critics inside and outside government have faulted him for not moving earlier and more effectively to push the kinds of measures later deemed necessary by the White House.

Officials said that Austin’s desire to avoid civilian casualties was a major factor in his decision-making. One former official said that instinct, while laudable, had translated into air combat rules so tight they made strikes less effective than they could have been.

James Jeffrey, who served as U.S. ambassador in Iraq, said Austin had done an “extraordinary” job halting the Islamic State advance given the limitations he faced. “What’s concerning to me, however, are these limitations and the general problem of the U.S. military seeing the military force as merely a contributing factor in any of these conflicts rather than a decisive element,” he said.

Austin declined to discuss interactions with civilian leaders but said he had worked to give straight-forward advice about issues in his purview. “I believe that military decision-making and military leaders shouldn’t be politicized,” he said.

Sen. John McCain (R-Ariz.), chairman of the Senate Armed Services Committee, has criticized the Obama administration as being overly cautious in Iraq and Syria.

“There are recommendations from these commanders including from Centcom, that end up in the black hole called the White House and the [National Security Council],” McCain said recently. “I don’t blame General Austin and Centcom . . . they’re just a funnel.”

Austin has been notable for his reluctance to speak in public about his views or the operations he oversees. One official described it as a blind spot. “Part of his role at that level is to carry policy water and to communicate policy decisions,” the official said.

Even within government, he has been reticent to share his personal views outside a small cadre of advisers, officials said. He is so private that even senior aides know little about the basic facts of his life.

“He’s a rare beast today in uniform that doesn’t seek attention . . . and doesn’t try to litigate command decisions” in the press, the former senior Pentagon official said.

That reserve has won Austin favor with a White House known for its distaste for leaks and appears to have helped repair civil-military ties that frayed in the early Obama years.

One recent episode may crystallize the basic dynamics of Austin’s tenure. In 2014, senior officials approved a Centcom plan, developed with White House input, to train more than 5,000 fighters in Syria.

From the start, it was plagued with problems. In September last year, Austin faced a withering response when he informed Congress that the $500 million program had trained only a handful of Syrians. McCain, incredulous, scolded Austin. “I have never heard testimony like this,” he said, finding fault with the strategy Austin defended. “Never.”

Soon afterward, Centcom abandoned the program in favor of a new approach. Austin “was smart enough to say this isn’t working,” a defense official said. “He knew he would get eviscerated by the armchair generals.”

A senior official said the training program, motivated by a desire to act, had been built on wishful thinking. “I don’t think that’s necessarily Lloyd’s fault,” the official said.

“There was a sense that ‘Oh, maybe this can work,’ ” the official said. “But that crashed on the shoals of the reality of Syria.”