Union of Utrecht Union of Utrecht The Union of Utrecht () was a treaty signed on 23 January 1579 in Utrecht, the Netherlands, unifying the northern provinces of the Netherlands, until then under the control of Habsburg Spain. The Union of Utrecht is regarded as the foundation of the Republic of the Seven United Provinces, which was not recognized by the Spanish Empire until the Twelve Years' Truce in 1609. The treaty was signed on 23 January by Holland, Zeeland, Utrecht (but not all of Utrecht) and the province (but not the city) of Groningen. The treaty was a reaction of the Protestant
Utrecht (province) the new Prince-Bishopric of Utrecht was formed. In 1122, with the Concordat of Worms, the Emperor's right of investiture was annulled, and the cathedral chapter received the right to elect the bishop. It was, however, soon obligated to share this right with the four other collegiate chapters in the city. The Counts of Holland and Guelders, between whose territories the lands of the Bishops of Utrecht lay, also sought to acquire influence over the filling of the episcopal see. This often led to disputes and consequently the Holy See frequently interfered in the election. After the middle of the 14th