To send into a midsummer tropical jungle an American army, untrained to take care of its health, for the most part clothed in the regulation army woolens, and tumbled together in two months, was an undertaking which-could be justified only on the ground that the national safety demanded immediate action. In 1898, however, it seemed to be universally taken for granted by people and administration, by professional soldier as well as by public sentiment, that the army must invade Cuba without regard to its fitness for such active service. The responsibility for this decision must rest upon the nation. The experience of centuries had proved conspicuously that climate was the strongest defense of the Caribbean islands against invasion, and it was in large measure the very sacrifice of so many American soldiers that induced the study of tropical diseases. In 1898 it could hardly be expected that the American command, inexperienced and eager for action, should have recognized the mosquito as the carrier of yellow fever and the real enemy, or should have realized the necessity of protecting the soldiers by inoculation against typhoid fever. Fixed as was the determination to send an army into Cuba at the earliest possible moment, there had been a wide diversity of opinion as to what should be the particular objective. General Miles wavered between the choice of the island of Porto Rico and Puerto Principe, a city in the interior and somewhat east of the middle of Cuba; the Department hesitated between Tunas on the south coast of Cuba, within touch of the insurgents, and Mariel on the north, the seizure of which would be the first step in a siege of Havana. The situation at Santiago, however, made that city the logical objective of the troops, and on the 31st of May, General Shafter was ordered to be prepared to move. On the 7th of June he was ordered to sail with "not less than 10,000 men," but an alarming, though unfounded, rumor of a Spanish squadron off the north coast of Cuba delayed the expedition until the 14th. With an army of seventeen thousand on thirty-two transports, and accompanied by eighty-nine newspaper correspondents, Shafter arrived on the 20th of June off Santiago.