The event marks the end of a decades-long campaign by the families of the two men to correct what they and many historians believe is an unjustified failure to honor all those involved in the so-called Great Locomotive Chase.

Shadrach and Wilson were among a group of 24 men who carried out the audacious plan in April 1862. They hijacked a train outside Atlanta and left a 90-mile-long trail of destruction through Georgia to the Tennessee border, with their enemies hot on their heels. When the pursuit finally ended, the attackers were captured and eight were executed. Most escaped, but some were held as prisoners of war for nearly a year.

Nineteen soldiers received the Medal of Honor — including the first ever awarded — for their role in the mission. (Some of them were honored posthumously.) Another soldier, captured before the attack began, later declined the award, historians said. Two others involved were civilians and did not accept the award.

In an emotional discussion with reporters on Tuesday, Shadrach and Wilson's descendants beamed with pride at knowing that their ancestors' efforts and their families' grassroots advocacy, along with historians, were finally being recognized.

Some of those who made the trip to Washington had known the story for a long time. Others, including Wilson's great-great-granddaughter Theresa Chandler, only learned from the Army four years ago that a prominent figure in the Civil War came from their lineage.

Now 85, she said a legacy that had almost been forgotten had been reshaped.

“I would have given anything,” she said, “to be able to say, 'Grandpa, tell me about it. … What was it like?'”

The mission arose from a desire to destroy the South's ability to move troops and military equipment.

Maj. Gen. Ormsby M. Mitchel, assigned by the Union to the Tennessee campaign, considered how best to attack Chattanooga, a well-defended Confederate citadel located on vital water and rail lines. In a frontal attack, the rebels could flood the area with reinforcements in rail cars from the South and overwhelm U.S. forces, he concluded.

James J. Andrews, a civilian Northern spy, devised a novel solution. A small team of volunteers would disguise themselves as civilians and travel 200 miles into Confederate territory, steal a locomotive, and then destroy tracks and burn bridges to cut off the secessionists' logistical lines.

The plan faced setbacks from the start, says Shane Makowicki, a historian at the U.S. Army Center of Military History. It had rained before the mission, making it difficult to detonate the bridges. The soldiers lacked tools and had to improvise, he says. And although some had experience with trains, there was little to no preparation beforehand.

“The fact that these men volunteered speaks volumes about their courage and heroism,” Makowicki said. “Today, people who do something like this have to undergo months or weeks of special training.”

The mission, led by Andrews, began north of Atlanta in what is now Kennesaw, Georgia, where the team captured a locomotive named the General and its three freight cars. Conductor William Fuller gathered a posse and gave chase on foot before taking over a trolley and eventually several other locomotives to catch up with the Union soldiers.

The task force made periodic stops to rip out railroad ties and cut telegraph wires to prevent other Confederate troops from learning of the attack. Oncoming trains on the single-track line forced the general to stop several times, according to an Army summary of the mission.

As Fuller and his party approached, the Union raiders aboard the General abandoned the locomotive 18 miles from Chattanooga because they no longer had enough wood to supply the locomotive, according to the Army. The men scattered, but were eventually all captured within two weeks.

Chattanooga fell the following year.

Andrews and seven others, including Shadrach and Wilson, were tried as spies and saboteurs and hanged. Jacob Parrott, who was severely beaten in captivity, was among those who survived the ordeal and later made history as the first soldier to receive the Medal of Honor.

Historians and family members could only speculate why Shadrach and Wilson were overlooked for so long. The unit was involved in heavy combat afterward, and officers who should have documented such feats were transferred to other units, said Brad Quinlin, a historian and author who advocates for the men's Medal of Honor.

Some members of the Shadrach family have been pushing for the award since the Carter administration, they said. A 2008 budget proposal included a provision to award the medal to the two men, but momentum didn't build until 2012, when Quinlin and family member Ron Shadrach met. They later presented new evidence to defense officials for review.

Although the mission ultimately failed, it is considered a landmark event in the Civil War and has been adapted into books and films, including Buster Keaton's 1926 The General and 1956's The Great Locomotive Chase.

Brian Taylor, Shadrach's great-great-great-nephew, said he was awestruck by the immersion in family history, and it deepened their relationship with his father. They affectionately call Shadrach “Uncle Stealer,” and Taylor once boarded the General, now a museum piece in Georgia.

Before the ceremony at the White House, Taylor played an acoustic guitar and crooned a song he wrote about the mission. “Do it for the glory, boys,” he sang, “because you might not find your way home tonight.”