It's difficult to imagine a "splendid" war. But that's how John Hay, U.S. ambassador to Britain and a good friend of Theodore Roosevelt, characterized a conflict with Spain 100 years ago. U.S. forces won a swift and decisive victory after suffering relatively few deaths and claimed a host of new territories overseas. As a result, the country began establishing itself as a formidable world power. When the fighting ended, an enthusiastic Hay said to Roosevelt, who had led a special cavalry unit, the "Rough Riders," in the war: "It has been a splendid little war, begun with the highest motives, carried on with magnificent intelligence and spirit, favored by that fortune which loves the brave." The conflict was the Spanish-American War, fought from April to August 1898. In it, the United States destroyed Spanish forces and took possession of major parts of Spain's 400-year-old empire, including Puerto Rico, the Philippines and Guam. America extended its territorial dominance overseas and joined imperialist European nations fast acquiring colonies in Africa and Asia. In the same burst of expansionist sentiment, the United States also annexed Hawaii, an independent country, shortly before the war ended. "We need Hawaii just as much and a good deal more than we did California," President William McKinley said then. "It is Manifest Destiny." McKinley was referring to a concept that dates from America's earliest days but a term coined in 1845 -- that American settlers and their descendants had a divine right to spread across North America and, some contended, beyond the continent, dominating ever larger parts of the world. Late in the 19th century, empire-building sentiment came from many of the most prominent American leaders such as Roosevelt, a future president whose "Rough Riders" helped win a key battle in Cuba, and Henry Cabot Lodge, a Massachusetts senator and father of Henry Cabot Lodge Jr., Richard M. Nixon's running mate in 1960. If America was to become one of the world's major military powers, these men said, it, too, should have an empire. A war with Spain, which had started empire-building in the New World when Christopher Columbus landed there in 1492, offered the means. "This was a time when the United States was ready for war," says David Frum, a historian and a senior fellow at the Manhattan Institute, a political think tank. "It was bursting with strength and looking for an opportunity to display how powerful it was. One thing the war did for the United States was demonstrate that it was potentially a first-rate military power and other people should treat it as such." The war undoubtedly came at a critical juncture for the United States but ranks low on the historical barometer of most Americans, particularly when compared with the Civil War or World War II. Still, the 1898 conflict left a distinct legacy. It elevated people such as Roosevelt to the status of national hero and helped to set the stage for conflict with Japan in World War II. It was the outgrowth of an event that remains one of the most enduring and compelling mysteries in American history -- the sinking of the U.S. battleship Maine, either by a Spanish act of war or an accident. Also, it generated slogans that would live for generations: "Remember the Maine!" and Adm. George Dewey's famous instruction to Capt. Charles Gridley at the Battle of Manila Bay in the Philippines: "You may fire when you are ready, Gridley." Finally, the war remains a powerful example of the power of the press run amok: In large part, the war was fomented by American newspapers using what now would be considered unethical journalistic practices. In the highly competitive climate of late 19th century journalism, influential American newspapers often sensationalized facts, deliberately trying to incite public opinion against Spain. The practice was called jingoism and "yellow journalism," the latter term coined from cartoons in the New York World and the New York Journal of "the yellow kid," a little urchin dressed in yellow. The World and the Journal, owned by Joseph Pulitzer and William Randolph Hearst, respectively, competed feverishly for readers, knowing that nothing boosts circulation like a war. Deliberately misleading reporting made it next to impossible for the United States and Spain to negotiate a peaceful settlement. Shortly after the Maine was destroyed, and without evidence whether the explosion was caused by a mine or an accident aboard ship, the papers intensified their exaggerations. The Journal carried a banner headline that charged: "Destruction of the Warship Maine Was the Work of an Enemy." The World, which asked, "Maine Explosion Caused by Bomb or Torpedo?" also published a diagram of what it called a secret "infernal machine" that struck the ship like a deadly torpedo. Hearst was driven by sensationalism and war more than Pulitzer, according to Richard Schwarzlose, a journalism professor at Northwestern University. The year before the war, when Cuban peasants were agitating for independence from Spain and newspapers were sending journalists to cover the conflict, Journal cartoonist Frederic Remington wired Hearst from a seemingly peaceful Cuba: "There will be no war. I wish to return." Hearst allegedly cabled back: "You furnish the pictures, and I'll furnish the war." The Cuban struggle for independence from Spain had begun in 1895 when, after four centuries of colonial rule, Spain suspended constitutional guarantees to the Cuban people. As a result, Cuban rebels began mobilizing under various leaders to drive out the Spanish. About 8,000 Cuban fighters organized to face 52,000 Spanish troops garrisoned on the island. Using guerrilla tactics, Cubans found success when they burned Spanish-owned plantations. Spain reacted brutally, massacring Cuban civilians and imprisoning others in disease-ridden camps, practices that caused more than 100,000 Cuban deaths. Clara Barton, who tended the wounded in the American Civil War and later would found the American Red Cross, set up hospitals in Cuba to aid soldiers and noncombatants from both sides. As the rebellion dragged on, many Americans turned against Spain, finding its treatment of Cubans intolerable and demanding that Presidents Grover Cleveland and McKinley, his successor in 1897, take steps to end the violence. Roosevelt, then assistant secretary of the Navy, made it known that he was increasingly frustrated by McKinley's "flabby" approach to Spanish tactics in Cuba. He complained that McKinley had "no more backbone than a chocolate eclair." Meanwhile, as the press tried to inflame tension between the United States and Spain, both nations tried to negotiate a peaceful solution. But a new round of violence erupted in Cuba in early 1898. To protect American citizens and business interests, McKinley sent the Maine, a sleek, powerful and costly warship, into Havana Harbor on the northern coast, where it docked Jan. 25. The U.S. government declared that the Maine was on a friendly mission. To avoid trouble, the ship's commanding officer, Capt. Charles Sigsbee, prevented his men from going ashore. At the same time, Roosevelt was itching for war, writing, "I wish there was a chance that the Maine was going to be used against some foreign power, by preference Germany but . . . I'd take even Spain if nothing better offered." The Maine was never used against anyone. About 9:40 on the misty evening of Feb. 15, with most of the 350-member crew asleep below deck, two explosions rocked the battleship. The forward third of the vessel was virtually obliterated, with about 250 sailors and two officers killed instantly. Scores of burned and injured men were fished from the harbor, and eight others died later. Sigsbee and most officers survived because their quarters were astern. That evening, Sigsbee sent a secret dispatch to Roosevelt in Washington, noting that the "Maine was probably destroyed by a mine. It may have been done by accident. I surmise that {a mine at the anchorage spot} was planted previous to her arrival, perhaps long ago. I can only surmise this." The captain added that a public verdict on the cause of the accident "should be suspended until further report." Six weeks later, a naval court of inquiry reported that a mine had detonated under the Maine, but it did not lay blame. Pressure intensified on McKinley, and several days later, he asked Congress to approve U.S. intervention. On April 21, 1898, the United States began establishing a blockade of Cuba. Two days later, Spain reluctantly declared war and, on April 25, America declared war on Spain, making the declaration retroactive to the 21st. Under the resounding cry, "Remember the Maine! The hell with Spain," America went to war. The first engagement occurred far away, 7,000 miles off the California coastline in Manila Bay in the Philippines. The lopsided battle quickly signaled U.S. military prowess over Spain. Adm. George Dewey was in Hong Kong with a fleet of six modern, steel-hulled cruisers when McKinley ordered him to the Philippines to capture or destroy a Spanish fleet based at the colony, partly to cope with Filipino insurrectionists seeking independence from Spain. McKinley was concerned that the Spanish ships might be used against the U.S. West Coast. "If the dons were victorious, they would likely cross the Pacific and ravage our Oregon and California coasts," McKinley later told the Christian Advocate newspaper. Dewey, who had served under Adm. David Farragut in the American Civil War, boldly sailed his fleet against the Spanish, who had anchored their 10 antiquated ships off the Philippine coast to protect Manila, knowing that a running battle against the American warships would be futile. On May 1 at 5:40 a.m., Dewey issued his famous call to Gridley, and U.S. guns blazed. American vessels made five runs past Spain's ships, and by noon, all were sunk, burning or abandoned. No Americans died, while the Spanish suffered 167 dead and 214 wounded. The stunning victory made Dewey a national hero, called "the conqueror of the Philippines." His image soon adorned merchandise bought eagerly by Americans who had barely heard of the Philippines but adored the man who acquired them for the United States. Spain's Pacific empire was history, and its Caribbean power was soon to crumble. In late May, America's North Atlantic Squadron under Rear Adm. William Sampson began to blockade a Spanish fleet anchored in the harbor at Santiago de Cuba, a Spanish stronghold on the island's southeastern coast. Sampson's fleet was joined by Commodore Winfield Schley's squadron, which had been created to defend America's Atlantic coastline from possible Spanish raids. For a month, U.S. ships shelled Spanish fortifications but could not enter the cul-de-sac harbor because of mines at its mouth. At about the same time, 15,000 U.S. troops were landed on Cuba and began marching toward Santiago. Then, on July 3, Sampson sailed away from the harbor, intending to confer with U.S. Army commanders on land. With the blockade momentarily weakened, Vice Adm. Pascual Cervera's Spanish fleet tried to flee the harbor, sailing single file east along the Cuban coast. Cervera's bold move launched one of the most decisive battles in U.S. naval history. With Schley in tactical command, Sampson's fleet chased the Spanish ships along the coast and attacked, burning them. Spain lost 1,800 men in the Battle of Santiago, compared with one dead and one wounded for the United States. Uncomfortable with such a lopsided victory, Jack Philip, captain of the USS Texas, told his jubilant crew: "Don't cheer, boys. The poor devils are dying." So many Spanish sailors were trapped on burning ships or leaping into the water that Capt. Robley Evans of the USS Iowa turned from attacker to rescuer. "I lowered all my boats," he told the Associated Press, "and sent them at once to the assistance of the unfortunate men, who were being drowned by dozens or roasted on the decks. I soon discovered that the insurgent Cubans from the shore were shooting men who were struggling in the water after having surrendered to us. I immediately put a stop to this, but I could not put a stop to the mutilation of many bodies by the sharks inside the reefs." While that battle was important in the defeat of Spain, the Battle of Manila Bay had greater long-term consequences for America, says Mark Hayes, a naval historian at the Washington Navy Yard. "The acquisition of the Philippines gave us an interest in the Far East," Hayes says, "and protecting our acquisitions and interests in the Philippines came in conflict with the Japanese, which led to our involvement in World War II. If we had not tried to take out the Spanish fleet in Manila and seize control of the Philippines, then the course of history would have been quite different." While the U.S. Navy was overwhelming the Spanish, the U.S. Army also had a job to do. American soldiers who had been marching toward Santiago attacked fortified hills near the city. Directing one division were Col. Leonard Wood, who had won the Medal of Honor for fighting Apache leader Geronimo, and Lt. Col. Theodore Roosevelt. Roosevelt had told McKinley that, if war came, he wanted to leave his post as assistant Navy secretary and go to the battlefront. He eventually sounded a call for 1,000 volunteers to join a newly created regiment known as the 1st U.S. Volunteer Cavalry. The motley group, nicknamed the "Rough Riders," consisted of privileged athletes from Ivy League schools, Western cowboys, sons of prominent citizens and assorted frontiersmen -- all made eager to fight by war sentiment stirred by U.S. newspapers. On July 1, in one of the war's most famous moments, the Rough Riders charged up Kettle Hill, outside Santiago, defeating Spanish troops occupying high ground. Roosevelt led the attack on horseback while his men, on foot, fought their way up the slope. A bullet nicked Roosevelt in an elbow. The Rough Riders, contrary to popular recollection, did not take nearby San Juan Hill. An African American regiment did. Fighting with the Rough Riders was the 10th U.S. Cavalry Regiment, a black unit that Spanish foes knew as los yanquis humados, or "the smoked Yankees." These men fought for the United States at a time when "Jim Crow" segregation dictated separation of the races. "Not only did six members of the 10th earn the Medal of Honor in Cuba, the best evidence points to Color Sgt. George Barry, a 30-year-veteran of the unit, as being the first to plant the American flag on San Juan Hill," Richard Bak writes in his 1997 book, The Rough Riders. "It was an honor that many white commanders and reporters were loath to admit." The rest of Shafter's contingent seized positions in other areas surrounding the city. By nightfall, U.S. troops were entrenched in ridges near Santiago after suffering 225 dead and 1,400 wounded. Like Dewey, the Rough Riders -- but not the African American unit -- soon became cultural icons, their images appearing on cigars and song sheets, among other items. The war soon would end. Spain's garrison defending Santiago surrendered on July 17, and one week later, U.S. forces invaded and easily captured Puerto Rico, an island that ever since has debated its ties to the United States, with some Puerto Ricans arguing for independence, like Cuba, others pushing for U.S. statehood and a third faction preferring to continue commonwealth status. Spain agreed to an armistice Aug. 12. But Dewey, apparently not realizing that a truce had been signed, ordered several contingents of U.S. soldiers the next day to enter and occupy Manila, which surrendered quickly. The Treaty of Paris concluded the war in December 1898. Spain freed Cuba and ceded Guam, Puerto Rico and the Philippines to the United States, which, in turn, paid Spain $20 million for public property in the Philippines. Although just 385 Americans died in battle, according to the Washington-based Center for Military History, 2,061 succumbed to tropical diseases such as malaria, yellow fever, dysentery and typhoid fever, and 1,662 were wounded. More than 20,000 returning troops were held in a tent camp on Long Island awaiting discharge, and many died there of tropical diseases. U.S. troops occupying the newly won Philippine colony, however, would fight for three more years. In 1902, they finally defeated Filipino insurgents seeking independence. U.S. forces suffered about 6,000 casualties, Filipinos an estimated 250,000. The Spanish-American war, in the end, was not such a "splendid little war." Still, the conquests created new U.S. responsibilities in foreign affairs. The nation became more assertive, flexing its political and military muscle to influence international policies. For example, the United States brokered a peace agreement in the 1904 war between Russia and Japan; just 10 years earlier, it had virtually ignored a war between China and Japan. Roosevelt, who had become president three years earlier after an anarchist assassinated McKinley, was awarded the Nobel Peace Prize for helping to orchestrate the 1904 settlement. "The United States more or less twisted Japan's arm to make an agreement with Russia," David Frum says. "The country suddenly said, This is our ocean, the Pacific.' " In retrospect, Mark Hayes says, U.S. entrance into the war was "embarrassing" for two reasons: The United States enjoyed a huge military advantage, and the Spanish have never been found responsible for destroying the Maine. Investigations in 1898 and 1911 were inconclusive as to what caused the explosion. In a comprehensive examination of the incident, Adm. Hyman G. Rickover wrote in 1976 that the blast probably was started by a fire in the ship's coal bunker, a finding also unproven. Why did the Spanish declare war on the United States if the odds against winning were so steep? "They wanted to save their honor," says Willard Frank, a historian at Old Dominion University who concentrates on the Spanish navy. "The last thing the Spanish wanted is a war with the United States . . . they had enough problems, and they didn't see America as the real enemy." But the United States played that role for 110 days, and the balance of global power would be altered for generations. Michael Richman is a freelance writer who specializes in American history and sports. His e-mail address is mrichman@erols.com. CAPTION: A decidedly hawkish Uncle Sam revels in the Spanish-American War in this 1898 cover of Leslie's Weekly, a popular magazine. CAPTION: "New Faces at Thanksgiving Dinner," an 1898 cartoon, reflecting America's paternalism and even its racism toward the newly gained colonies. CAPTION: The 9th and 10th U.S. Colored Cavalry fights with the Rough Riders in a battle near Santiago. CAPTION: Theodore Roosevelt, center, poses with two Rough Riders while the new unit trained in San Antonio, Tex.