As President Obama was preparing to outline his strategy regarding Iraq and Syria, Massachusetts Democrats turned out a sitting congressman and nominated an Iraq veteran who is absolutely opposed to deploying ground troops in the region—and absolutely determined to avoid the incremental missteps that lead back toward war.

While Seth Moulton supported the president’s decision to provide humanitarian assistance to Iraqi civilians in the face of imminent genocide as “the morally right thing to do,” the candidate has raised tough questions about sending US military advisers to the region. “We must be very careful not to put American combat troops on the ground in Iraq,” says Moulton, “and I remain deeply concerned about the risk of civilian casualties when airstrikes are used without direction from ground forces.”

Moulton says the instability and violence that has torn at Iraq—particularly in regions where the Islamic State movement is active—represents “a political crisis resulting from a complete loss of trust in [former] Prime Minister Maliki and his increasingly sectarian government. This must ultimately be met with a political solution, not a military response.”

In statements and interviews during his congressional campaign in northeast Massachusetts, Moulton made a compelling and consistent—as well as highly nuanced—case for avoiding the sort of military response that would steer US forces back into Iraq. And he did so with authority, as both a progressive Democrat who has opposed George Bush’s war in Iraq and a Marine veteran who served four tours of duty in Iraq from 2003 to 2008.

On Tuesday, Moulton swept to an easy victory over Congressman John Tierney, an eighteen-year incumbent who was the first and only House Democrat to be defeated in a party primary this year. Moulton still faces a fall contest with a well-known and well-funded Republican, but most observers agree the challenger’s greatest hurdle was the primary. Though Tierney was vulnerable, at least in part because of an old gambling scandal involving his wife and brother, few thought the incumbent would be defeated until the final weeks of the campaign.

It was during those final weeks that the Democratic primary debate took up the issue of Iraq—with both candidates seeking to position themselves as antiwar contenders. Questions of war and peace were certainly not the only ones on the agenda, but they were, as The Boston Globe noted, “in play.”

Tierney made the point that he voted against authorizing George Bush and Dick Cheney to go to war at a time when popular sentiment was divided on the issue. And the incumbent’s supporters argued that he deserved credit not just for his vote but for his foresight.

But Moulton’s campaign made a compelling case that he would come to Congress as a war-wary representative with profound knowledge of the region. “Although Seth was firmly against the Iraq War, Seth served his country and led his platoon—eventually serving four tours of duty in Iraq over five years,” the campaign noted. “Seth led an infantry platoon during the 2003 invasion and was in the first Marine company to enter Baghdad. Later, he worked to establish independent Iraqi media. The following year, Seth returned to Iraq as an infantry platoon commander and fought in the lead company in the Battle of Najaf.”

That knowledge was on display when Moulton explained the dangers involved in dispatching substantial numbers of military advisers to Iraq—as the president has already done. An Associated Press profile of the candidate began by recalling that “Seth Moulton’s opposition to another ground war in Iraq is rooted in firsthand experience acquired from four tours. As a young Marine, he saw how quickly a militant threat could transform U.S. military advisers into a force entangled in the months-long battle for control of Najaf, some 100 miles south of Baghdad.”

And Moulton reinforced that point, saying, “Americans have to realize that when the president says he’s sending military advisers to Iraq, make no mistake, these are US special forces or Marines or Rangers or other units that are American ground troops.”

That’s an insight that Moulton brings to debates about military intervention—an insight that has, too frequently, been missing, not just in the debate about what to do now but in debates about US military actions going back to Vietnam. Memory and experience matter when complex issues of war and peace are in play. And it matters, in particular, when there are candidates who place themselves in what Moulton describes as “the long tradition of men and women who served and then used their public positions to speak out against war.”