Flushing, the port of Zeeland, which commanded the approach to Antwerp; and the inhabitants were compelled to take the oath to the prince of Orange, as stadtholder of the king.
The stadtholder summoned a meeting of the states of Holland and Zeeland to Delft, and on the 25th of April an act of federation between the two provinces was executed.
The authority conferred upon Orange as stadtholder by the provinces of Holland and Zeeland was thus ratified, but that astute statesman had no confidence that Philip intended to observe the treaty any longer than it suited his convenience.
Despite his youth he was made stadtholder of those two provinces and president of the council of state.
In 1588 he was appointed by the States-General captain and admiral-general of the Union, in 1590 he was elected stadtholder of Utrecht and Overysel, and in 1591 of Gelderland.