Dordrecht received its charter in 1220, the earliest in the county of Holland, and grew rich on the staple right that obliged goods moving down the Rhine, Meuse and Waal to be unloaded and offered for sale there. The Saint Elizabeth's flood of 1421 broke the surrounding polders and turned the town into an island, which it has remained, and the drowned land to the south became the marsh now managed as a nature reserve.
In July 1572, with the revolt against Spain barely begun, delegates of twelve towns met in a Dordrecht monastery in the first assembly of the States of Holland not convened by the royal governor, and agreed both to recognise William of Orange as stadtholder and to allow the exercise of Catholic and Reformed worship alike. Dutch tradition treats that meeting as the beginning of the republic. The city was a printing centre and a place where a synod could sit without the crowding of Amsterdam or the university politics of Leiden, and a national synod had already met there in 1578, which is part of why the international assembly of 1618 was sent to it as well. The 1572 assembly is also where the Dutch revolt acquired its religious character in a form that lasted.
The delegates guaranteed freedom of worship to Catholics and Reformed alike, a promise the Reformed party did not keep for long, and the gap between what was undertaken in Dordrecht in 1572 and what was enforced afterwards is a standing subject of Dutch historical argument. The city kept its printing houses through it all, and the 1618 synod met in a place already used to publishing what it decided.