The Dutch declared their independence from the
Habsburg king of Spain in 1579, which resulted in war. In 1580, the
Iberian Union, which combined the crowns of Spain and Portugal, was formed. Subsequently, king
Philip closed Portuguese ports to the Dutch and established a ban on trade between the Portuguese-Spanish colonies and the Dutch Republic. The Dutch attempted to restore the trade with the Portuguese colonies by occupying the
northeast of Brazil,
São Tomé Island,
Goree and
Elmina, which led to conflicts between the
Dutch Empire and the Iberian Union. On 1 December 1640, a revolution initiated in
Lisbon by the Portuguese nobility and high
bourgeoisie ended the
Iberian Union, leading to the ascension of
John IV of Portugal to the Portuguese throne. In the same year, the
Portuguese Restoration War began. John IV sent ambassadors to
France,
England, and the
Dutch Republic, in the hope of forging partnerships with these countries in his fight against Spain. ==Signing and ratification==