Following the First Union of Brussels (9 January 1577) the Estates-General concluded a second union on 10 December 1577 reaffirming its commitment to secure the withdrawal of Spanish forces from the Netherlands. Drafted at the insistence of William of Orange, it represented an attempt to promote cooperation between Roman Catholics and Calvinists, who were growing increasingly uneasy in their joint alliance.
See also Wars of Religion.
Historical Dictionary of Brussels. Paul F. State.