Nevertheless Dewey proceeded to blockade Manila, which was besieged on the land side by the Filipino insurgents under Aguinaldo.

This siege was indeed an advantage to the Americans as it distressed the enemy and gave an opportunity to obtain supplies from the mainland.

Dewey, however, placed no confidence in Aguinaldo, and further was instructed by Secretary Long on the 26th of May as follows: "It is desirable, as far as possible, and consistent for your success and safety, not to have political alliances with the insurgents or any faction in the islands that would incur liability to maintain their cause in the future." Meanwhile foreign nations were rushing vessels to this critical spot in the Pacific.

On the 17th of June, Dewey sent a cable, which had to be relayed to Hongkong by boat, reporting that there were collected, in Manila Bay, a French and a Japanese warship, two British, and three German.

Another German man-of-war was expected, which would make the German squadron as strong as the American.
The presence of so large a German force, it was felt, could hardly fail to have definite significance, and therefore caused an anxiety at home which would, indeed, have been all the keener had Admiral Dewey not kept many of his troubles to himself.