The first the fleet knew of the capture was when the Helena came steaming up with her prize and signaled the flagship. The other ships cheered and the Helena, started off for Key West, the Jover being worked by its own men, superintended by the prize crew. VALUABLE PRIZE CAPTURED. The most valuable prize yet taken was the transatlantic liner, Catalina, which was taken by the Detroit. The vessel's tonnage was 6,000, and with its general cargo the prize was considered worth nearly $600,000. The big ship was bound from New Orleans to Barcelona, via Havana, with a large general cargo. Twelve miles before making port the steamer was stopped by two shots, and a prize crew under Ensign H. H. Christy, consisting of sixteen men from the Detroit and New York, was put on board to take the vessel back to Key West. In addition to these notable captures the torpedo boat, Porter, took the Spanish schooner, Antonio, laden with sugar for Havana, and the revenue cutter, Winona, added the Spanish steamer Saturnine to the list. If it had not been for the excitement of taking occasional prizes, the blockading of Havana would have been dull business for the Jack Tars aboard the North Atlantic squadron. Saturday night they had to listen to the roar of the guns of Morro Castle and see the flashes of fire from their muzzles, without a reply from the fleet. Havana officials have declared that the discharge of those guns was only for signaling purposes and was not an attack on the fleet, but it would be difficult to make the sailors believe that Spanish marksmanship was not responsible for the fact that no balls fell near them. SPAIN DECLARES WAR. The Spanish government did not wait for further aggression on the part of the United States, but herself made the next formal move by issuing a declaration of the fact that war existed, and defining the conditions under which the Spanish government expected to carry on the conflict. This decree was gazetted in Madrid on Sunday, April 24, in the following terms: Diplomatic relations are broken off between Spain and the United States, and the state of war having begun between the two countries numerous questions of international law arise which must be precisely defined chiefly because the injustice and provocation come from our adversaries and it is they who, by their detestable conduct, have caused this grave conflict.