Flag of Poland

"The flag of Poland consists of two horizontal stripes of equal width, the upper one white and the lower one red. The two colors are defined in the Polish constitution as the national colors. ... Proportion 5:8. ... White and red were officially adopted as national colors in 1831. They are of heraldic origin and derive from the tinctures (colors) of the coats of arms of the two constituent nations of the Polish-Lithuanian Commonwealth, i.e. the White Eagle of Poland and the Pursuer of the Grand Duchy of Lithuania, a white knight riding a white horse, both on a red shield." [Flag of Poland. Wikipedia]