The postcards were handed down to Thuillier by her grandmother when she was a teenager.
The postcards are "mostly banalities, chit-chat about what was going on at home or on the front," said Thuillier. "(But) I'm here today it's thanks to them."
There's one part of the couple's 100-year-old correspondence that Thuillier does not have the love letters Day sent Charbonneau from the front, which she took with her to the grave.
Paris' National Library is one of dozens of collection points across France that opened their doors from Nov. 9 to 16 for the "Grande Collecte."
Donors were invited to tell the stories behind their mementos, which the library's experts scanned and entered into an online archive that has already collected more than 50,000 items.
Thuillier brought in other family heirlooms, including Day's military medals and ribbons, a black-and-white photograph of Day in uniform, and a well preserved green notebook in which Day's army career is detailed.
One item in particular interested Thuillier. It's a postcard written in Cyrillic, taken from the pocket of a Bulgarian soldier who her grandfather killed in combat on the Eastern Front. Thuillier says she dreams of being able to track down the soldier's descendants and return the postcard, a century later.
Some other material collected during the campaign:
Soldier Auguste Girard's medals and engraved certificate showing where he had fought and when he was discharged on Nov. 13, 1918.
A book of hand-drawn maps and notes evoking fighting in Champagne and elsewhere.
A pipe and plaque belonging to artilleryman Andre Truffaut.
A photo of the capture of a German soldier by French troops.
A mini-sword belonging to her grandfather brought by Josette Farat.
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On the web: http://www.europeana1914-1918.eu
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