A French historian who was a recognized expert on the D-Day invasion was sentenced to 364 days in prison for stealing dog tags and numerous other relics of U.S. servicemen whose planes crashed during World War II, officials said Tuesday.

Antonin DeHays, whose research focused on events at the French beach at Normandy, where President Dwight D. Eisenhower's troops launched the D-Day invasion, pilfered nearly 300 dog tags and other war relics during visits to a public research room of the National Archives in College Park, Maryland.

The systematic thefts by DeHays, a 33-year-old native of Normandy, took place during visits to the research room from 2012 to 2017. The published historian used his researcher identification card to access the artifacts.

On Tuesday, Archivist of the United States David S. Ferriero said he was relieved to hear of the historian's sentence and remained appalled by the thefts.

"His sentence sends a strong message to others who may contemplate stealing our nation's history," Ferreiro said. In an impact statement provided to the court, Ferreiro said the National Archives has spent tens of thousands of dollars reviewing the materials DeHays stole and seeking to recover items from third-party purchasers. He said the full loss from the archives may never be known.

DeHays peddled the majority of the stolen items on eBay and elsewhere to unwitting buyers. He made thousands of dollars selling many of the 291 dog tags and 134 records, including personal letters, photographs and small pieces of U.S. aircraft downed during the war.

Court documents show he tried to lure one prospective buyer with gritty details of the airmen's dog tags, saying some were burnt or showed stains of fuel and blood, describing them as "very powerful items that witness the violence of the crash."

He didn't sell everything. Officials say he kept some items at his home in College Park, which were seized during a raid, and even donated the stolen dog tags of a downed Tuskegee airman to a military aviation museum in Virginia in exchange for the chance to climb inside a single-seat fighter airplane from World War II.

At his Monday sentencing at U.S. District Court in Greenbelt, Maryland, DeHays told the court that he sold the stolen items in part to acquire a collection for his dream museum. The Washington Post quoted DeHays as saying: "At that time I saw it as a sacrifice I had to make if I wanted my dream to come true." Judge Theodore Chuang, who sentenced DeHays, said he committed "an egregious, morally repugnant crime." Following his prison stint, DeHays is due to spend three years on probation, including eight months in home confinement. He had faced a maximum sentence of 10 years in prison.