Germany got back two 400-year-old law books Tuesday from a former American soldier who took them as souvenirs from a salt mine storage vault in the closing months of World War II.

Robert Thomas was an 18-year-old member of George Patton's Third Army, 90th Division, when he took the books — one in Latin, the other in German. He returned them to German Ambassador Klaus Scharioth in a ceremony Tuesday at the National Archives building.

"The books will go home because it's the right thing to do," said Thomas, of Chula Vista, Calif., at the ceremony.

Thomas was recuperating from wounds caused by "Screaming Mimis," the German Nebelwerfer artillery rocket, sustained as he and other soldiers fought to break the Siegfried line, invade Germany and end the war in Europe. Thomas said a young lieutenant pulled him out of his recuperation center, and they rode a motorcycle into Ransbach, where people were hanging out white flags.

There they found a mine, 2,500 feet below the surface, that contained some 2 million books.

At least 15 million books were lost to U.S. and British bombers as they pounded the German heartland ahead of the eventual invasion, according to U.S. archivist Greg Bradsher.

The Germans stored valuables in monasteries, castles and other redoubts until after the Allied invasion of Normandy in June 1944. Salt mines were chosen as well for their ability to protection the artifacts by absorbing moisture.