In August 1615 a Dutch East India Company yacht Jakatra captured the Portuguese junk Santo Antonio off the coast of Japan. The junk represented the first prize captured by the Dutch in Japanese waters despite a number of attempts, and it provoked an outcry from the Portuguese and their supporters in Nagasaki. This paper reconstructs the chain of events precipitated by the arrival of Jakatra and her prize. Using internal correspondence and resolutions from the Dutch factory in Japan, the first part of the paper examines how the Company’s agents took their case to the shogun’s court in 1615, and the favorable decision they secured. The repercussions of the Santo Antonio incident were far-reaching. The incident persuaded Company administrators, particularly the highly aggressive Governor-General Jan Pieterszoon Coen, that the Company could―with virtual impunity―launch extended privateering campaigns against Portuguese shipping sailing to or from Japan, even to the extent of attacking enemy vessels in the shogun’s harbors. In the second part of the paper I consider the 1617 and 1620 campaigns launched by Coen against the Portuguese, and the response by Nagasaki officials and the bakufu that these campaigns prompted. Finally, I attempt to situate the Dutch East India Company's privateering activities within the broader history of maritime East Asia.