I can't tell if it's original or not. The characters written are mostly people's names. But there are also a few short messages written.
盡忠報國:Be repay the country with utmost loyalty.
滅私奉公:Renounce personal gain and dedicate yourself to the country.
祈御奮斗:I wish you the best of luck in your endeavors.
武運長久:May your victory last long.
忠勇義烈:Be Loyalty, Courage, Righteousness.