"Pro Concordia Labor" is the motto of the Peace Flag adopted in 1897. It was adopted to stand as a symbol for anyone working on behalf of peace, humanity, universal brotherhood, cosmopolitan values and a notion of 'patriotism' that transcends state loyalty. The colors were chosen so that the flag would not be confused with any other nation's flag. The motion adopting the flag in 1897 by the U.S. National Council of Women can be read below.
Kim Hyeyeon, Hope Elizabeth May and Dr. Chung Koo-do, chairman of the No Gun Ri Peace Foundation in front of the Peace Palace, The Hague (September 5, 2013).