In Flanders the town of Breda was taken after a famous siege.
But after his mediation in the treaty of Breda (July 1667), when Hugues de Lionne, secretary of state for foreign affairs, had isolated Spain, he substituted soldiers for the jurists and cannon for diplomacy in the matter of the queens rights.
Tournai, Maastricht, Breda, Bruges and Ghent opened their gates, and finally he laid siege to the great seaport of Antwerp. The town was open to the sea, was strongly fortified, and was defended with resolute determination and courage by the citizens.
On the 1st of May he signed the first draft of a treaty at Breda with the latter, in which he accepted the Solemn League and Covenant, conceded the control of public and church affairs to the parliament and the kirk, and undertook to establish Presbyterianism in the three kingdoms. He also signed privately a paper repudiating Ormonde and the loyal Irish, and recalling the commissions granted to them.
He left Brussels for Breda, and issued in April 1660, together with the letters to the council, the officers of the army and the houses of parliament and the city, the declaration of an amnesty for all except those specially excluded afterwards by parliament, which referred to parliament the settlement of estates and promised a liberty to tender consciences in matters of religion not contrary to the peace of the kingdom.