French État-Major Généraux, 2nd & 3rd Republic button.

The button — French État-Major Généraux, 2nd & 3rd Republic
The design shows the French republican arms: an eagle surmounting a fasces with a star, surrounded by cannon, anchors, and military trophies — the standard device used on French general staff buttons of this period.
The date range:
∙ The French Second Republic ran from 1848 until Napoleon III’s coup established the Second Empire in 1852. The Third Republic ran from 1870, when the Second Empire collapsed after the Franco-Prussian War, through to 1940 when France fell to Germany.
So “circa 2nd & 3rd Republic” means roughly 1848–1870 and 1870–1940, with the practical overlap period for this button style being c.1848–c.1900.