The Marquis de Lafayette, commander of the new National Guard, combined  the colors of the King (white) and the colors of Paris (blue and red) for his guardsmen's uniforms and from this came the Tricolor, the new French flag.

"Arise children of the fatherland
The day of glory has arrived
Against us tyranny's
Bloody standard is raised
Listen to the sound in the fields
The howling of these fearsome soldiers
They are coming into our midst
To cut the throats of your sons and consorts!"

The Marseillaise see all the lyrics and listen to the song

It began as a French marching song, and later became the French National Anthem

The French Revolution took on the character of a religious crusade. It was not enough to have a revolution at home. The gospel of revolution must be spread to the rest of Europe. France declared war on Prussia and Austria as the French "nation" against foreign kings, and proclaimed it advanced the cause of liberty.