France

The French flag was Introduced in 1848 by the French Second Republic. Three colors of the French flag blue, white and red stand for the French revolution of equality and fraternity and liberty respectively.
The flag was initially created in 1790. However, the colours were the reverse of what they are today.
The flag went out for Napoléon's defeat at Waterloo. But it was brought back in 1830 (again by Lafayette) and remained in use ever since. The significances have been associated with the colours these are all spurious and designed after the fact. 
Colours of the flag
The flag of France has three major colours "combine" different symbols, designed after the fact:

•    Blue represents Saint Martin, a rich Gallo-Roman administrator who ripped his blue coat with his sword and offered one half to a poor who was begging him in the snow. This colour is the symbol of care, of the obligation that the rich had to help the poor.
•    White represents the Virgin Mary, to whom the Kingdom of France was blessed by Louis XIII in the 17th century. White became the color of Royalty. The King's vessels flown plain white flags at sea.
•    Red represents Saint-Denis, the saint patron of Paris. The original oriflamme (war banner) of the Kings was the red oriflamme of Saint-Denis.