The Multiple wars were erroneous with the US government successfully lobbying wars of "Bringing Liberty" to the various areas that in reality the US was attempting to take as states or Annex the territory from the Spanish. Over the course of the series of war many Spanish colonies clung to their former mother-nations for fear of running into American Expansionism. This pushed the Spanish empire to remain a major imperial power for next few Decades as their colonies and Viceroyalties clung to them as long as possible.
This sentiment lasted until the First South American colonies began to Secede just after the First Spanish American war. This large scale flight while the US fought for influence over South America. Both the US and Spanish lost the majority of South American Influence to the Empire of Brazil following the Second Spanish American War.
The Third and Final war was a major conflict and the full scale invasion of Cuba, and the Philippines which were finally added to the United States after the Havana and Manila campaigns. These campaigns brought Spain's declining colonial empire to a close.
1st Spanish American War
The First Spanish American war, was a conflict ranging over six months from September 2nd 1819 to March 5th 1820. The Outcome of this war was the loss of the Texas session and the entirety of North American New Spain above the Mexica Empire. This conflict surprised the European powers as many expected the United States to attack the more highly populated Cuba and Puerto Rico. However the US instead using its overland connection to New Spain braced its ports from the inevitable Spanish assault on the Eastern US and Invaded New Spain with nearly 400,000 troops.While definitively outmatched and outgunned by the Spanish navy the US navy opened the engagement in the Caribbean in an attempt to get an early shot at the Spanish before they could bring the full force of their navy. The Americans managed to secure a sizable time period to bide their time following the first naval battle of of Hispaniola. This battle bought the Americans valuable time in organizing their coastal defenses and procuring more ships to fight the Spanish navy. While for the next six months American naval forces all throughout the Caribbean were thoroughly paralyzed after this in the opening battle, Spanish blockades were prevented on key American cities by the Americans managing to win the Battle of the Chesapeake, and the Battle of Charleston. These two battles effectively sealed the fate of the American coastline in favor of the Americans.
The End of the War in March concluded when the Spanish and local authorities were finally Defeated deep in New Spain just 4 miles south of the Rio Grande river. The Battle of the Rio Grande was the decisive battle of the war despite the naval battle at Hispaniola. The Rio Grande battle ended in favor of the Americans as the Spanish troops suffered from bad leadership, long supply lines from the Forts and Bases in Northern Mexico, and the exemplary service of soldiers, veterans of the War of 1812, which also ended in an American Victory (due to the fact British lacked a major continental presence.)
2nd Spanish American War
The Second Spanish American war was an informal influence war in 1853 which sought to Displace Spanish influence from the Rest of their colonies and establish a Pan-American sphere of Influence and possibly gain some bases on the Continent. The War involved less than 100,000 troops on either side and led to only a few short Naval skirmishes. By Proxy however the Aztec Empire surviving to this day to their own credit and good international conflict exploitation, were undergoing the Aztec Civil war in which Factions influenced by the US and its governmental systems as well as educated leaders led to the Civil war between the Federalist, and Imperialist faction. The Spanish began to back the Imperialists hoping to subjugate the Aztecs after so many years and end a threat on their colonies, ended up opposing the United States by Proxy as the US secretly backed the Federalists intent on establishing a friendly Mexica Republic.
The US Army at this point was deployed on the Border with the Aztec Empire with the Spanish Directly to the south of the Aztec empire. However in 1853 during Willard Fillmore's presidency successful Congressional lobbying brought about the US policies of Manifest destiny continuing. This forced Fillmore's hand and he agreed to fight this unsung war with Spain and become more adoptive of manifest destiny after he challenged French annexation of Hawaii. By the end of the Two year civil war in the Aztec Empire the next president taking over Franklin Pierce who ended up offering the decisive supplies and weapons needed to the Mexica revolutionaries.
The War lasted from 1853-1855 and saw the rise of the heavily US supported and controlled Mexica republic. The Republic automatically began renewed attacks against the Spanish less than a year later and eventually brought about the collapse of the remaining Spanish colonial governments in Central America. The Mexica, however, did not take advantage of the newly small and independent Nations due to the isolationist and reservist policies of its new congress.
Ironically the War was lost majorly by both sides as the Spanish lost its remaining influence in South America which it had slowly regained in Colombia and Venezuela, to Brazil as they began to exert its newly found considerably improving aspirations to the rest of the continent establishing its own bloc.
Third Spanish-American War
The Third Spanish American war was the final conflict between the Spanish and United States regarding American colonies and possessions lasting from April 25 1898 to August 12 1898 and saw the loss of Cuba, Puerto Rico, The Philippines, and Guam to the United States and began the Final Realization that the United States had emerged as a Leading Global power Alongside the British and French Empires.The Conflict was instigated by Yellow Journalism of the harsh treatment of Cubans which was erroneously printed in newspapers which outraged the American public. While initially used to sell more copies it galvanized the American public against the Spanish in Cuba and just Spain in General. The Spanish who were suffering a Crisis of governments following the concurrent failure of their government ever since restoration post Napoleonic wars. The Spanish were initially very sure that the Americans had no reason to declare war and invade but when the USS Maine blew up in Havana harbor the American public forced the government's hand and war was declared.
The Following conflict brought about the domination shown by US naval power, and the subsequent invasion of both Pacific and American possessions of the Spanish. The Spanish while some units notably fought well, were defeated in a matter of months as American forces proved absolutely supreme. The Spanish suffered from naval leadership and modern deficiency which eventually proved to be Spain's most major flaw. By the time Cuba had fallen the Spanish had pulled back their most modern fleets to protect Spain proper and when the Americans offered peace Spain readily accepted.
The final Spanish American war was seen as the Americans final step in achieving Global power status. Over the years the US had gained much territory, huge industry, and finally its own colonial possessions in which they now ruled. The US and Vinnish Kingdom fighting barely years apart brought about the true recognition of the American nations rise on the Global positions especially with the Empire of Brazil continuing to act as major player in the near future as well.