The Union of Utrecht was an alliance based on an agreement concluded on 23 January 1579 between a number of Dutch provinces and cities, to reach a joint commitment against the king, Philip II of Spain. By joining forces, they hoped to force him to stop his harsh administrative measures. In addition, some important political matters were regulated in areas such as defence, taxation and religion, which is why the treaty in question is also seen as a first version or precursor of a later constitution. The Union of Utrecht complemented the so-called General Union of 1576, established by the Pacification of Ghent, which is why it is also referred to as the Further Union.