13 August
After a "Negotiated" engagement, Manila surrenders to Admiral Dewey and forces under his command. Though the armistice had been agreed upon in Washington the day before, it was understood by all at this time, due to communications lag, that any gains made before the receipt of a cease fire order are recognized as pursuant to that order. The modern assumption of an "unnecessary" engagement does not, and has never applied to these circumstances. (a peeve of mine)
The armistice order would be received by both sides in the Phillipines on August 16. This marks the formal end of the combat phase of the Spanish American war.