Having won the Battle of Manila Bay, Commodore George Dewey immediately recognized that, while he could now compel Manila's surrender, the city could not be occupied without a strong force of soldiers. He also soon became aware of the dual risks of a Spanish relief expedition and intervention by another power. Responding quickly to his cabled request for reinforcements, the U.S. Government made arrangements to dispatch Army forces and additional warships.

Three groups of soldiers were sent as rapidly as they could be gathered and trained. The first contingent left San Francisco in three transports on 25 May and arrived in Manila Bay at the end of June. Another four transports steamed through the Golden Gate on 15 June, arriving on 17 July. The third group, embarked in six ships, departed on 27 June and reached Manila Bay at the end of July. More soldiers and Marines were sent after the war's conclusion.

The few major warships left in the eastern Pacific were also ordered to reinforce Dewey. The cruiser Charleston accompanied the first Army expedition, bringing with her a much-needed ammunition resupply. To provide the Asiatic Squadron with heavy firepower, the monitors Monterey and Monadnock left California in June. Each escorted, and to some extent towed, by a collier, these slow ships were nearly two months in passage. Monterey was ready in time to help with Manila's capture, while Monadnock arrived a few days after the Spanish surrender.