The flag of Portugal is a rectangle-shaped vertical bicolor featuring a field unequally divided into green, on the hoist, and red, on the fly. The lesser version of the national coat of arms (armillary sphere and Portuguese shield) is centered over the color boundary at equal distance from the upper and lower edges. Portugal officially adopted this design for its national flag on June 30, 1911-replacing the one used under the constitutional monarchy-after being chosen, among numerous proposals, by a special commission whose members included Columbano Bordalo Pinheiro, Joao Chagas, and Abel Botelho.
The new field colors, especially green, were not traditional in the flag's composition and represented a radical republican-inspired change that broke the bond with the former religious monarchical flag. Since a failed republican insurrection on January 31, 1891, red and green had been established as the colors of the Portuguese Republican Party and its associated movements, whose political prominence kept growing until it reached a culmination period following the Republican revolution of October 5, 1910. In the ensuing decades, these colors were popularly propagandized as representing the hope of the nation (green) and the blood (red) of those who died defending it, as a means to endow them with a more patriotic and dignified, therefore less political, sentiment.
The current flag design represents a dramatic change in the evolution of the Portuguese standard, which had always been closely associated with the royal arms. Since the country's foundation, the national flag developed from the blue cross-on-white armorial square banner of King Afonso I to the liberal monarchy's royal arms over a blue-and-white rectangle. In between, major changes associated with important political events contributed to its evolution into the current design.
The Portuguese flag displays three important symbols: the colors of the field, the armillary sphere and the national shield (these two make up the coat of arms).