The Union of Arras (Dutch: Unie van Atrecht, Spanish: Unión de Arrás) was an accord signed on 6 January 1579 in Arras, under which the southern states of the Netherlands, today in the Wallonia region of Belgium and the Nord-Pas-de-Calais (and Picardy) régions in France, expressed their loyalty to the Spanish king Philip II and recognized his Governor-General, Don Juan of Austria. It is to be distinguished from the Union of Utrecht, signed later in the same month.