Spanish-American War reunited the United States
The American Civil War, aka, The War Between the States, ended after four bloody years in 1865.
Bitterness and recrimination over the horrendous losses suffered on both sides poisoned the long period of Reconstruction. The assasination of President Lincoln, once the defunct Confederacy's mortal enemy, now the best hope of reconciliation, was a mortal blow to reconciliation. The premature death of Southern hero, Robert E. Lee, in 1870, who could have prevented the rise of the Klu Klux Klan, also dealt a death blow to peaceful reconciliation.
Carpetbaggers and southern scalawags introduced corruption into the devastated South which only deepened the bitterness.
Union victory reunited the north and south politically, but not emotionally, not psychologically, and not spiritually.
The southern people did not think of themselves as Americans but as a defeated people. For the first and only time in its history, a large part of the American people experienced the humiliation and shame of unconditional surrender.
The former Confederate states remained under federal occupation from 1865 to 1877, a total of 12 years.
Defeated Nazi Germany remained under Allied occupation only 10 years.
Defeated Imperial Japan remained under American occupation only 6 years.
The Spanish American War brought the southern and northern peoples together again. The memories, bitterness, and wounds of the Civil War, only 33 years previously remained there, but now there was common cause for the American people to rally around together. The United States emerged victorious over the tottering Spanish empire and recognized as a world power. The southern American people, joyful over military victory and national stature, began to view themselves as Americans once again.
The devastation of former Confederacy was so complete that it was not until the 1980s that the South regained its full political power. Regaining its economic prominence took almost as long.
The United States government of 1898 was generous and conciliatory with Spain. Though victorious, the U.S. paid the Spanish government 20 million dollars for the Philippines, a huge sum at that time. Spain lost its few remaining colonies like Cuba and Puerto Rico to the U.S., small loss to Spain. But the U.S. did not demand harsh reparations or terms from Spain. As a result of these conciliatory relations, the Spanish people of 2008 do not harbor any bitterness towards the United States. It's doubtful if many Spaniards today think much about the Spanish-American War any more than most Americans today who can't even remember the war. Today in 2008 the United States and Spain remain firm NATO allies.