Pfc. William Regan from St. Paul was killed by Japanese small-arms fire in the Solomon Islands during World War II. He earned a Distinguished Service Cross and is the subject of an online biography by Mary Peterson. (The Minnesota Star Tribune)

The 22-year-old machine-gunner from St. Paul was half a world away from home when Japanese small-arms fire caught him in the Solomon Islands on July 20, 1943.

Pfc. William A. Regan Jr., U.S. Marine Corps, kept firing until he fell, earning a Distinguished Service Cross for his valor and becoming one of more than 9,700 Minnesotans who would be killed or wind up missing in action in World War II.

Regan would have turned 99 on Monday, when the nation pauses to commemorate its fallen warriors against the backdrop of the COVID-19 pandemic. He's buried beneath a granite military marker at Calvary Cemetery in St. Paul.

And Regan is the subject of a recent online biography written by Mary Peterson of Austin, Minn., one of an all-volunteer army of history buffs and researchers trying to make sure WWII servicemen and women aren't forgotten 75 years after the war.

The initiative started when Utah banker Don Milne, 59, saw his job eliminated earlier this year. He'd been blogging tirelessly, writing military bios nearly every day for the past three years and posting them on what would have been the subject's 100th birthday. At last count, he'd written 1,200.

"While 1,200 may sound like a lot of stories, there were 400,000-plus Americans who did not come home from the war," he said.

Realizing he could never write about them all, Milne started a nonprofit called Stories Behind the Stars and started assembling a network of fellow WWII researchers like Peterson.

The daughter and wife of men who worked in the Hormel hog-kill operation in Austin, Peterson, 72, retired in 2012 from the business office of Austin's Riverland Community College. With time on her hands, she got the WWII-research bug digging into the story of her uncle, Army Air Corps Sgt. Kermit Olstad of Blooming Prairie, Minn. Olstad was a waist gunner in a B-17 bomber that was shot down over Germany in 1944, killing him at the age of 22.

"It was his 27th mission," Peterson said, "and my mother never talked about her brother."

She shared her story about Olstad with relatives and posted it on Fold3, the military arm of ancestry.com. Her path crossed Milne's on WWII blogs and Facebook pages, and he asked her to write up a bio on Regan, whose birthday fell on Memorial Day this year.

Peterson called Milne back in an hour and said she was done. He called her "a common citizen who has taken up a task to write about our nation's WWII fallen so they will not be forgotten."

Peterson spends up to five hours a day writing military stories. She's lost count but has produced about 50 so far, including bios of the seven other men killed when her uncle's bomber went down.

She's since cranked out bios of service people from her home turf of Mower County and is branching out to Steele and Freeborn counties in southern Minnesota.

"There's just a fascination for me to tell these stories so they're not forgotten," she said. "Uncle Kermit's story was talked about so little, it prompted me to do others."

Milne just launched the Stories Behind the Stars nonprofit, securing funding from the the Greatest Generations Foundation and persuading ancestry.com to waive fees for his volunteers.

"I already have people from 21 states interested in joining me to write the stories of the WWII fallen," Milne said, listing Peterson among his prize recruits.

He added that with free access to research sites, volunteers just "need to free up some time to write these stories. And a lot of people have extra free time these days."

Despite all kinds of information floating around on genealogy and military websites, Milne said it's often tricky to find detailed back stories. For example, Regan's death generated only one paragraph on the bottom of page 7 of the Minneapolis Star Journal on Aug. 7, 1943, more than two weeks after he died.

Six-foot-tall with brown eyes and hair, Regan attended St. Paul Central and Cretin high schools and the University of Notre Dame. Before joining the Marines, he worked on a construction crew building what became known as the Twin Cities Army Ammunition Plant in Arden Hills.

Regan's Distinguished Service Cross, the second-highest military decoration after the Medal of Honor, was awarded five months after his death. "Although dying," his citation reads, "he continued through sheer courage and zealous devotion to duty to man the gun and directed a fiercely effective fire until he collapsed."

Peterson's research shows Regan's only sibling, Sarah Kelly, had seven children. "So there should be lots of nieces and nephews out there," she said.

Eventually, Milne hopes to develop a smartphone app that will allow visitors to military cemeteries to scan the soldiers' names on gravestones and get an immediate link to their story.

"Imagine," he said, "how more enriching a visit to Fort Snelling National Cemetery would be."

Curt Brown's tales about Minnesota's history appear each Sunday. Readers can send him ideas and suggestions at mnhistory@startribune.com. His latest book looks at 1918 Minnesota, when flu, war and fires converged: http://strib.mn/MN1918.