[1][2] On 31 January 1578 the Spanish cavalry commanded by John's nephew, Don Alexander Farnese, Prince of Parma (Italian: Alessandro Farnese, Spanish: Alejandro Farnesio), after pushing back the Netherlandish cavalry, attacked the Netherlandish army, causing an enormous panic amongst the rebel troops.

[12][13] The Union of Brussels had 25,000 fighting men, but these troops were badly equipped and led, and above all very diverse: Dutch, Flemish, English, Scottish, Walloon, German, and French, and religiously ranging from staunch Catholics to zealous Calvinists.

[21] De Goignies and a large number of his officers were captured,[3] along with thirty-four flags and banners and all the artillery and baggage of the Netherlandish army.

[13] Around 3,000 rebels reached Gembloux and closed the gates, but after negotiations they surrendered to the Spanish on 5 February, sparing the city from a sack.

[6] The defeat at Gembloux led to military pressure on Brussels, causing the States General of the Netherlands to leave and move to Antwerp.

[22] Prince William of Orange, the leader of the revolt, also left, along with its nominal governor, Matthias of Austria (the future Holy Roman Emperor), who had accepted the position of governor-general by the states-general, although he was not recognized by his uncle, Philip II of Spain.

He was succeeded by Farnese as governor-general (last desire of John that Philip II confirmed), who at the head of the Spanish army reconquered large parts of the Low Countries in the following years.

[4] On 6 January 1579, the provinces loyal to the Spanish Monarchy signed the defensive Union of Arras, expressed their loyalty to Philip II and recognized Farnese as Governor-General of the Netherlands.