The AP reports that Chile has returned 3,778 books its forces stole from Peru's national library ... in 1881. "The volumes, written in Greek, Latin, French and Spanish, some with full-page colonial-era maps, dated from the 16th to 19th centuries. Chile shipped the books, most in excellent condition, to Peru this week via DHL ..."
Chile's national director of libraries, archives and museums, Nivia Palma, called the action a "concrete expression of our deep commitment to building a relationship of brotherhood and cooperation between our countries."
The books were taken after the capture of Lima by Chilean forces during the 1879-1883 War of the Pacific.
Just for fun: if Peru's national library charged 10 cents a day for a late book, I think that works out to ... $17,375,022 (not taking inflation or currency into account).