The flag of Portugal was adopted on June 30, 1911. The flag is rectangular and divided into two vertical fields: a smaller green field on the left side and a larger red field on the right side. The Portuguese coat of arms, surrounded by the armillary sphere, is centered on the dividing line between the two color fields.
Although the red and green colors on the flag may not seem significant today, the color choice and design of the flag represented a radical shift towards a Portuguese republic. Until the late nineteenth century, Portugal had been governed by religious monarchs and used a white flag with a blue cross. During a revolt on January 31, 1891, however, the Portuguese Republican Party established red and green as their official colors. Within the next two decades, Portuguese Republicans began to associate the green with the hope of the Portuguese nation and the red with the blood of those who died defending the country. After the flag’s development, the Republican party quickly propagandized the red and green colors and included them on nearly every republican item.
The armillary sphere that appears around the Portuguese shield commemorates the Portuguese sailors of the Age of Exploration, the two-hundred-year period between the fifteenth and seventeenth centuries, during which Europeans ventured into unknown seas and arrived in Africa, North and South America, and Asia. The armillary sphere was essential for navigation and was also used in many architectural works, including the Jerónimos Monastery and Belém Tower.
The Portuguese shield appears in the middle of the armillary sphere. The shield has been the unifyig element of Portuguese flags throughout the centurie–despite the Republican revolution–and it is the oldest Portuguese symbol. Inside the white area of the shield are five smaller blue shields, or quinas. The symbolism behind these shields comes from the “Miracle of Ourique,” a tale in which Afonso I, a Portuguese ruler, is visited by a divine messenger who assured him that God was watching over him. Shortly afterwards, Afonso and his troops defeated five Moorish kings and their troops. In gratitude, Afonso incorporated the five quinas, which are arranged in a cross pattern, into the shield’s design. The seven castles on the shield represent Afonso III’s victory over seven Moorish fortresses in 1249.