The Peace-treaty of Munster in 1648 was the end of the 80-year war in The Netherlands. It was the liberation of the Republic of the Netherlands (de Republiek der Nederlanden) of the Spanish occupation.
After the dark period of war and suppression it allowed for international expansion and eventually lead to what was later called 'the Golden Century': flourishing trade, art and culture.

See also the Union of Utrecht commemorative 2.50 guilder coin.

(Thanks to Roel Muller.)