Tom Diaz of Northwest Washington looks over some of the memorabilia from his father’s time in the military. (Katherine Frey/The Washington Post)

As Tom Diaz sat in the Army band hall waiting to hear his late father’s music for the first time, he had a troubling thought: What if it’s lousy? What if the march his father wrote for Gen. George S. Patton Jr. during World War II was a stinker?

Diaz knew that his father, Gregorio A. Diaz, had written the “Third Army March” in 1945. But he’d never heard it. It hadn’t been played in ages. And his father had been dead for 24 years.

Now, as the Army concert band prepared to record it for the first time, Diaz braced himself.

Lt. Silas N. Huff, associate conductor, told the band that the son of the composer was present. The band applauded. Huff raised his baton. What followed was a rousing, jaunty, toe-tapping piece of superb march music.

“Yeah!” Diaz thought, as he listened, “It’s really good.”

The first recording of the "Third Army March," performed on Nov. 6, 2013, by the U.S. Army Concert Band, a component of the U.S. Army Band. (Courtesy the U.S. Army)

The recording, one day this month at Joint Base Myer-Henderson Hall in Virginia, capped a story of an impoverished immigrant musician who joined the Army in 1924 and wound up becoming the band leader for one of most famous generals of World War II.

It brought back rich memories for his son.

“What a moment,” Tom Diaz, 73, of Northwest Washington, said. “Knowing everything I know about my father, having grown up as an Army brat . . . it’s almost a sense of unreality that this is actually happening.”

The recording also culminated a 15-month quest to restore the march to prominence by Lawrence A. Devron, the former Army musician who rediscovered it last year. He had found, to his dismay, that the modern incarnation of the Third Army, U.S. Army Central, uses the popular “Patton March,” from the 1970 film “Patton” for ceremonies, not the original.

No one there had ever heard of the march Diaz created over a half-century ago.

The story began in June 2012, when Devron, who works for the Army records management and declassification agency, was visiting Shaw Air Force Base in South Carolina, the main command post of U.S. Army Central.

During the visit, Devron was touring part of the installation with the command’s archivist, Kathy Olson, when he spotted a drum major’s mace and sash in a trophy case.

The theme for Franklin James Schaffner's "Patton" (1970). (Youtube/JokerRecordings)

Devron, 67, of Springfield, Va., who had played French horn in the Army Band in the 1960s, was curious. He asked if he could take a closer look.

“When I looked in there . . . I saw this piece of manuscript,” he said. It was written on now-aging paper and was dated April 10, 1945.

“I looked at it real close, and it was the ‘Third Army March.’ ”

“That’s great!” he told Olson, who had assembled the items in the case. “I’ve never heard that piece.’”

“Neither have we,” she replied. “There’s no recording of it.”

“I said, ‘Well, what do you play . . . at Third Army ceremonies?’ ” Devron asked.

“The theme from the movie ‘Patton,’ ” Olson said.

Devron thought, “I got a mission.”

For the ‘big boss’

Warrant Officer Gregorio Diaz was 39 when he composed the march in April 1945 in Germany.

“Respectfully dedicated to Lt. Gen. George S. Patton Jr. and the gallant officers and men of the Third U.S. Army,” he wrote on the title page of the condensed score.

The war in Europe was almost over, and Patton’s Third Army was famous for dashing across France, saving America forces at the Battle of the Bulge and pushing into the heart of Nazi Germany.

Patton, himself, had become a legend. Flamboyant, controversial and brilliant, he would say at war’s end that commanding the Third Army had been the highlight of his life.

His men returned the affection. Gregorio Diaz, a diminutive man, referred to Patton as the “big boss.”

Diaz’s 61st Army Ground Forces Band had been chosen by Patton to serve as the Third Army’s official band.

“It wasn’t just some band,” Tom Diaz said. “Gen. Patton had a very high standard. He liked pomp and circumstance and music, and this was the band he wanted for his Army headquarters.”

It was an honor for Gregorio Diaz, who had been born in a poor village in the Canary Islands and left home when he was 12. He’d made his way to Mexico, crossed into the United States in 1924, and went right to Fort Bliss, Texas, where he enlisted in the 7th Cavalry’s band, his son said in an interview.

He apparently had learned clarinet and saxophone while playing in a youth band in his home village.

In the Army, he moved among several different bands in Colorado, Panama and Washington, becoming leader of the 61st Ground Forces band on June 7, 1944, the day after Allied forces landed in Normandy on D-Day, according to his military service record.

Gregorio Diaz finished the march less than a year later.

“He wanted to call it ‘The General Patton March,’ ” Tom Diaz said. “I think Gen. Patton thought that was, even for his ego, too much. So they called it the ‘Third Army March.’ ”

It’s a “pass in review” march that lasts for about three minutes, enough to allow a band to pass in front of a reviewing party. It’s a light, European-style march — more festive than martial.

There is a snapshot of Patton, in gleaming helmet and knee-high boots, purportedly listening to the march’s debut in Luxembourg. Another photo depicts Patton watching the band march by, with Gregorio Diaz in the forefront.

And Tom Diaz has a snapshot of his father talking to Patton, who is much taller, and another man. On the back is written, “Big Boss, his aide, and ‘me.’ ”

Sitting dormant

Lawrence Devron, who did not know Tom Diaz, was determined to find out more about the old march in the trophy case.

After the war, the Third Army became an administrative headquarters back in the United States and then was deactivated in the 1970s, Devron said. Olson, the archivist, said she suspected that its band was also deactivated then.

The march faded into obscurity. A U.S. Army Central spokesman said he did not know exactly why.

Devron, the son of a prominent Washington dance-band leader, said he was motivated, in part, by one of his old music teachers, who used to tell students, “Music is a dead art. You must make it live.”

He started contacting friends, music experts and Army band alumni. “I said, ‘What do you know about this? Nothing. Is there a recording? No,’ ” he said.

He got a copy of the condensed score via e-mail but said it’s difficult to extrapolate a full score from a condensed score. He asked the Army band to do some research, and the band located other parts in its library.

“The march has been played,” Devron said. “That’s never been the issue. The issue is it’s been dormant for all these years, and nobody [had] ever recorded it.”

Plus, it was historic. “How many guys have a chance to compose something” like that, he said. “The Schwarzkopf ceremonial march? Have you heard that?” he said. “The Colin Powell march?”

“It’s a rare thing that a guy can . . . dedicate a piece that the [general] has listened to and blessed,” he said.

He started lobbying the Army band to get the march recorded.

“Third Army does not need to be playing the ‘Patton’ theme only,” he said he argued. “That’s not its history.”

The band agreed, and the recording session was scheduled for 11 a.m. Nov. 6 in the band’s Brucker Hall.

Devron and Tom Diaz were both present. “I’ve been working on this for a year and three months,” Devron said. “I was delighted.”

As he sat listening to the music, Tom Diaz said he thought of his father — how he would listen to opera on the radio, how he loved the music of John Philip Sousa, and how he had showed up at the front door with a big duffel bag when the war was over.