The first weeks of the war were confined chiefly to naval operations. A blockade of Cuban ports was established and pretty well maintained, beginning along the central and western part of the north coast on April 22. A number of small Spanish vessels were captured, and there were some bombardments of shore towns and exchanges of shots with Spanish gunboats. Despite the vigilance of the American scouts and blockading squadrons, Admiral Cervera with several powerful Spanish warships, sailing from Cadiz on April 8 and touching at Martinique on May 11, succeeded in entering the harbor of Santiago on May 19. There he was soon besieged by a more powerful American fleet under the command of Commodore, afterward Admiral, Schley; who on June 1 was joined by Admiral Sampson, who thereafter took command. Lieutenant Victor Blue was sent ashore on June 11, to make a long detour to the hills back of the city, from which he was able to see and identify the Spanish ships. Meantime Lieutenant Richmond P. Hobson with seven picked men in the early morning of June 3 took the big coal hulk _Merrimac_ in to the narrowest part of the harbor entrance and there sunk it with a torpedo, hoping thus to block the passage and prevent Cervera's ships from coming out. The exploit was not entirely successful, the vessel not being sunk at quite the right point, though it did make exit much more difficult. Hobson and his comrades were taken prisoners by the Spaniards, but were treated with distinguished courtesy and consideration in recognition of their daring exploit. Thereafter the blockading fleet kept close watch day and night upon the harbor mouth, brilliantly illuminating it with searchlights all night, to prevent the escape of the Spanish fleet. Meanwhile General Nelson A. Miles, commander of the United States army, was preparing for an invasion of the island. The Fifth Army Corps was organized at Tampa, Florida, under the command of Major-General William R. Shafter, and on June 14 was embarked on a fleet of 37 transports. This fleet sailed around Cape Maysi to the southern coast of Cuba, and on June 21 was off Santiago. General Shafter and Admiral Sampson went ashore to confer with General Calixto Garcia at his camp at Acerradero, and found the situation by no means as encouraging as they had hoped. Garcia had only about 3,500 Cubans in his force, and they were not all well armed, and there were 1,000 more at Guantanamo. General Shafter's army numbered fewer than 16,000 men. Against these the Spaniards under General Linares numbered about 40,000.