The significantly more powerful United States Navy squadron, consisting of four gunboats, two armed tugs and a patrol yacht, overpowered a Royal Spanish Navy squadron which consisted of four gunboats, three pontoon used as floating batteries and three transports, sinking or destroying all the Spanish ships present without losing a single ship of their own.

On the third attempt, all U.S. naval elements in the area, reinforced by two Wilmington-class gunboats combined forces under the command of Chapman Coleman Todd to destroy the Spanish vessels once and for all.

The seven-ship force split into three different groups and entered the harbor at the same time to ensure the Spanish vessels had no path of escape.

Upon the outbreak of war, the United States Navy had placed a blockade around the island of Cuba, both to assist the local revolutionaries fighting against Spanish rule, and to hamper Spanish efforts to resist the American expeditionary forces by ensuring they could not move around men and supplies to areas which required them.

The port of Manzanillo had been a refuge for Spanish troop transports and blockade runners (many of which were requisitioned merchant steamships) since the outbreak of war, and the United States Navy had already dispatched two reconnaissance expeditions to the harbor to determine its defenses.

While Young's force knocked the Spanish gunboat Centinela out of action on its approach to the harbor, accurate fire from other Spanish gunboats within the harbor, Estrella, Guantánamo, and the Delgado Parejo forced an American withdrawal, with only three casualties and damaged vessels to show for their efforts.

[8][9][10] Wrote one American sailor:[11] We have been in two of the bombardments off Santiago and helped clear the way for the troops at Daiquiri, yet we had seen nothing before to equal the accuracy, rapidity, and uniformity of the fire that the Spanish forces gave us at Manzanillo.

Some fifteen minutes later, the Scorpion and Osceola replied by opening fire on the shore batteries, although they likewise were unable to score any hits.

The American vessels continued their advance into the harbor, but they soon ran into issues with the shallow depth of Manzanillo's bay, forcing them to reconnoiter passages so that the deeper-drafted gunboats, the Wilmington and the Helena, would not beach themselves accidentally.

[24] Advancing upon the Spanish positions, Todd realised that his forces were focusing too much of their fire upon transports taking refuge in the harbor alongside the immobile pontoon present, the hulk and storeship Maria, and ordered the Helena to switch to targeting the cornered gunboats instead of assisting the Willmington with finishing the transports and pontoon off.