The report from the commission investigating the Maine disaster was in the president's hands by 25 March. It concluded that the cause of the explosion was external, and most Americans immediately assumed that Spanish agents had been responsible for it. With war sentiment building up throughout the country and in Congress, McKinley continued to urge caution, still hoping that negotiations might bring an end to problems in Cuba. On 27 March, Secretary Day cabled Woodford outlining the administration's last plan. The final ultimatum called for an immediate armistice and reiterated McKinley's offer of arbitration. Shortly thereafter, Day warned that unless Spain capitulated immediately, public pressure would compel the president to ask for a declaration of war. McKinley feared that if he did not respond to the pressure, his supporters would desert him. Congress might then take matters into its own hands and declare war without McKinley's requesting it.
The Spanish reply to McKinley's ultimatum arrived at the White House on 1 April. It assented to arbitration of the Maine affair, abandonment of re-concentration in the western provinces, acceptance of American financial assistance, and a relief program for Cuba. Yet Spain agreed neither to suspend hostilities nor to approve American mediation. In Madrid, Woodford thought that the Spanish ministry knew it had lost Cuba but preferred war to mediation. Nevertheless, he pleaded for more time to work out a solution.
For McKinley, time had run out, and he began drafting a message to Congress asking for a declaration of war. At the last minute, on 10 April, he received a communiqué from Woodford indicating that the queen regent had consented to suspend hostilities and move toward autonomy for Cuba. Given the state of public and congressional opinion, it was too late. McKinley asked for intervention on 19 April, and Congress granted his request the next day, adding only the Teller Amendment, which renounced any intention to annex Cuba. A formal declaration of war followed within a week.
Americans greeted the coming of war with celebration. Patriotic fervor stilled the criticism of McKinley, and as commander in chief he found himself enormously popular throughout the land. Men from all walks of life were eager to share in the expected American triumphs, and enlistments soared. Yet it was with good reason that McKinley had questioned the fighting readiness of the armed forces. Despite a year's warning, they remained unprepared.
Numbering only 28,000 men and officers, the army had watched as the navy, the nation's first line of defense, received most of the $50 million appropriated in March. Now, suddenly increasing to more than 250,000 troops, land forces faced immense if not insurmountable problems in supply and logistics. Half of the volunteers never left training camps during the war, and many of those who did were issued winter woolen uniforms for warfare in the tropics. If all the troops mobilized had seen combat, some of them would have seen it without ammunition, for there was not enough to go around. Selected as the point of embarkation, the Port of Tampa proved an unfortunate choice. Only one railroad connected the city with its inadequate piers. Boxcars backed up for miles, cargoes disappeared in the confusion, and troops found themselves compelled to take matters into their own hands, relying on their wits for survival.
The navy fared better than the army, in part because it escaped the pressures of rapid expansion, and in part because for fifteen years it had kept abreast of innovations in maritime technology. Beyond that, McKinley and his secretary of the navy could rely on commanders who had given much thought to strategy should hostilities begin. It is not surprising, then, that the navy won the first great American victory. In the fall of 1897, Commodore George Dewey had received command of the Asiatic squadron, and with the declaration of war, he was ordered to proceed from Hong Kong to the Philippines. By 30 April the squadron was at the entrance to Manila Bay, where Admiral Montojo had anchored the sizable but decrepit Spanish fleet. The following day, the American force sailed into the bay and annihilated Montojo's fleet without sustaining a loss.
Attributing the Maine explosion of the previous February to Spanish treachery may have led many Americans to overestimate enemy strength. At Manila the Spanish were actually incapable of effectively returning fire from their ancient hulks, and mines planted in the channel had no fuses. Yet participants could celebrate the victory as a convincing demonstration of American naval power. When the American people learned of it a week later, they were ecstatic, and they immediately gave Dewey an honored place in their pantheon of heroes. McKinley, more concerned with pursuing the war to a successful conclusion, authorized an expedition to capture and occupy the Philippines. Though the Americans did not take Manila until after Spain had signed a peace protocol, it was clear that the United States had become a power in the Far East. The ramifications of that development were many, and American foreign policy was to undergo momentous changes in the postwar period.
After Dewey's victory, attention turned to the Caribbean theater and to plans for an invasion of Cuba. Actually carrying out the attack was complicated by the confusion in Tampa, by lack of agreement among high-ranking officers in the army, and by Secretary Alger's failure to provide either leadership or coordination. Alger's vanity led him to promise more than was possible, and his arrogance led him to blame others for his inability to meet commitments. In the army itself, supervision of all operations, at least theoretically, rested with Major General Nelson Appleton Miles. The appointment he held provided very little real power, he disliked McKinley personally, and he nurtured hopes of using his military reputation to gain high political office. More important for the moment, Miles opposed rushing off helterskelter to invade Cuba. He favored postponing the assault until fall, when cooler weather and better training of troops would assure success. A third principal in the military drama that was taking on some of the characteristics of comic opera was General William R. Shafter, who by reason of seniority took command in the field. Cautious and corpulent, he was a prototypical product of the army's bureaucracy. Yet he showed good sense, and while he did not inspire the troops to heroic achievement, his caution reduced casualties.
Although McKinley might have recognized the merit in arguments for postponing an invasion until fall, he was acutely conscious of political pressures that called for immediate action. Furthermore, the navy was to share in the operation, and Secretary Long strongly urged that it get under way. McKinley's patience with Alger and the army was wearing thin, and he finally decided to move. The fleet of Admiral William T. Sampson and Commodore Winfield Scott Schley blockaded Santiago on 6 June, and the following day McKinley ordered Shafter to transport his troops to Cuba. The operation was scarcely a model of military efficiency, but by 29 June it had come within a mile and a half of Santiago.
The Battle of San Juan Hill, which took place on the city's outskirts during the first two days of July, was bloody but inconclusive. Shafter grew despondent and thought of retreat, but then the navy saved the day. Contained in Santiago Bay, the Spanish squadron of Admiral Pascual Cervera y Topete began sailing out of the harbor on 3 July to challenge the ships of Sampson and Schley. Within hours the destruction of Spanish sea power was complete. "The fleet under my command offers the nation as a Fourth of July present the whole of Cervera's fleet," read the cable from Sampson.
The victory at Santiago Bay signaled an early conclusion of hostilities. Rather than attack the city itself, Shafter negotiated its surrender on 17 July. With that surrender the fighting in Cuba petered out, and only Puerto Rico remained as the last vestige of Spanish empire in the western hemisphere. McKinley had already authorized operations to take the island, and an American expedition quickly accomplished that objective a few days before Spain sued for peace. After meeting with the cabinet, McKinley laid down the American terms: Spanish evacuation of Cuba; cession of Puerto Rico to the United States as an indemnity; and American occupation of Manila, pending final treaty agreement. Spain balked at the last provision, but McKinley would not budge. The Spanish finally capitulated on 10 August, and the war came to an end.