The national flag of France is a tricolour featuring three vertical bands coloured royal blue (hoist side), white, and red. The flag of France is known to English speakers as the French Tricolour or simply the Tricolour.

The royal government used many flags, the best known being a blue shield and yellow fleur-de-lis on a white background, or state flag. Early in the French Revolution, the Paris militia, which played a prominent role in the storming of the Bastille, wore a cockade of blue and red, the city’s traditional colours. According to Lafayette, white, the “ancient French colour”, was added to the militia cockade to create a tricolour, or national, cockade. This cockade became part of the uniform of the National Guard, which succeeded the militia and was commanded by Lafayette. The colours and design of the cockade are the basis of the Tricolour flag, adopted in 1790.The only difference was that the 1790 flags colours were reversed. A modified design by Jacques-Louis David was adopted in 1794. A solid white flag was used during the Bourbon restoration from 1815 to 1830, the tricolour was brought back into use after the July Revolution and has been used ever since.

Blue and red are the traditional colours of Paris, used on the city’s coat of arms. Blue is identified with Saint Martin, red with Saint Denis. At the storming of the Bastille in 1789, the Paris militia wore blue and red cockades on their hats. White had long featured prominently on French flags and is described as the “ancient French colour” by Lafayette. White was added to the “revolutionary” colours of the militia cockade to “nationalise” the design, thus creating the tricolour cockade. Although Lafayette identified the white stripe with the nation, other accounts identify it with the monarchy. Lafayette denied that the flag contains any reference to the red-and-white livery of the Duc d’Orléans. Despite this, Orléanists adopted the tricolour as their own. Wikipedia