Return of the Oegyujanggak Uigwe
Also called: Return of the Royal Protocols from France
The 297 volumes of uigwe looted from the Oegyujanggak by French troops in 1866 came back after 145 years.

Mobius6 · CC BY-SA 4.0 · Source
During the French Campaign of 1866, French troops carried off uigwe and other books from the Oegyujanggak library on Ganghwa Island and burned the building and the rest of its books. Park Byeong-seon, then working at the Bibliothèque nationale de France, found the uigwe there in 1975 and made them known, and the government and civic groups pressed for their return for decades. President Mitterrand brought one volume on his 1993 visit to Korea, but the rest stayed in France.
Under an agreement between the two presidents at the 2010 G20 summit in Seoul, 297 volumes returned in four shipments in April and May 2011. France kept ownership and lent them on a loan renewed every five years, a limitation often pointed out. Many are royal reading copies, and some are unique. They are held at the National Museum of Korea.