Book excerpt: The Twelve Years Truce of 9 April 1609 made a temporary end to the hostilities between Spain and the Northern Netherlands that had lasted for over four decades. The Truce signified a crucial step in the recognition of the Republic of the Northern Netherlands as a sovereign power. As the direct source of inspiration for the 1648 Peace of Munster the Truce is a crucial text in the formation of the early modern law of nations. As few other texts, it reflects the radical changes to the laws of war and peace from around 1600. The Twelve Years Truce offers a collection of essays by leading specialists on the diplomatic and legal history of the Antwerp Truce of 1609. The first part covers the negotiation process leading up to the Truce. The second part collects essays on the consequences of the Truce on the state of war. In the third part, the consequences of the Truce for the sovereignty of the Northern and Southern Netherlands as well as it wider significance for the changing laws of war and peace of the age are scrutinised.