High Quality Content by WIKIPEDIA articles! The Dutch Pacification Campaign on Formosa was a series of military actions and diplomatic moves undertaken in 1635 and 1636 by Dutch colonial authorities in Formosa (modern-day Taiwan), aimed at subduing hostile aboriginal villages in the south-western region of the island. Prior to the campaign the Dutch had been in Formosa for eleven years, but did not control much of the island beyond their principal fortress at Tayouan, and an alliance with the town of Sinkan. The other aboriginal villages in the area conducted numerous attacks on the Dutch and their allies, with the chief belligerents being the village of Mattau, who in 1629 ambushed and slaughtered a group of sixty Dutch soldiers.