The death of Isabel on November 29, 1633, shattered finally any hopes that the peace party in the Provinces (for there was a strong peace party) might have had of arriving at any satisfactory agreement.
By the decease of the arch-duchess, who had been a wise and beneficent ruler and had commanded the respect and regard not only of her own subjects but of many northerners also, the Belgic provinces reverted to the crown of Spain and passed under the direct rule of Philip IV.

The Cardinal Infante Ferdinand, fresh from his crushing victory over the Swedes at Noerdlingen, came as governor to Brussels in 1634, at the head of considerable Spanish forces, and an active renewal of the war in 1635 was clearly imminent.
In these circumstances Frederick Henry determined to enter into negotiations with France for the conclusion of an offensive and defensive alliance against Spain, the common enemy.

He had many difficulties to encounter.

The Estates of Holland, though opposed to the terms actually offered by the Brussels government, were also averse to taking any step which shut the door upon hopes of peace.

Richelieu on his side, though ready, as before, to grant subsidies and to permit the enrolment of French regiments for the Dutch service, shrank from committing France to an open espousal of the Protestant side against the Catholic powers.