How did the U.S. expand from a country affected by a civil war to a "new empire" at the turn of the XXth Century?

The American Civil War was a war fought from 1861 to 1865 between the United States (the "Union" or the "North") and several Southern slave states that had declared their secession and formed the Confederate States of America (the "Confederacy" or the "South"). The war had its origin in the fractious issue of slavery, and, after four years of bloody combat (mostly in the South), the Confederacy was defeated, slavery was abolished, and the difficult Reconstruction process of restoring unity and guaranteeing rights to the freed slaves began.

The American Civil War was one of the earliest true industrial wars. Railroads, the telegraph, steamships, and mass-produced weapons were employed extensively. The mobilization of civilian factories, mines, shipyards, banks, transportation and food supplies all foreshadowed World War I. It remains the deadliest war in American history, resulting in the deaths of an estimated 750,000 soldiers and an undetermined number of civilian casualties.

 "Killing ground: photographs of the Civil War and the changing American landscape". John Huddleston (2002). Johns Hopkins University Press. ISBN 978-0-8018-6773-6. Viewed cover November 28, 2012.

After such a terrible chapter in the developing history in The United States, where American's fought American's the aftermath indicated

• Loss of human life
• Material destruction
• Strenghtenness of the union and the expansion to the west
• Secession initiatives stopped
• Urbanization and industrial character over the rebuilt cities
• Quick process of postwar reconstruction they gain RETRUST so the reintegration process is fast.
• The country began a class conflict process marked by polarization
  created through wealth, misery and political violence.

 From Early XIX Century to Mid-XIX Century, very little attention was put to foreign affairs as the Civil war dominated all aspects of politics in the U.S. but there seemed to be 2 interests that guided America in

its pursuit of foreign interests:

1.  Pursue favorable trade agreements and alignments to acquire territory and exert power over the Pacific and the Caribbean
2. Foster the spread of Christian and democratic ideals within the continent.(MANIFEST DESTINY)

The reconstruction and evolution of the empire tooked place from 1865-1913 within 3 specific scenarios:

• Economy (Industrial Revolution):

The "North" who now controlls Congress starts passing laws to protect northern products against cheap European goods, this helped the founding of American industrial complexes. (FACTORIES = JOB OPPORTUNITIES = FLOW OF ECONOMY = FINANCIAL EQUALITY)

• Politics (Military Strenghtness):

The American-Spanish War

Important facts:

- U.S. declares war against Spain but  they have NO wishes to annex Cuba. (1895)

- It is the first international conflict where the U.S. Army and Navy intervene.

- A quick victory for the U.S. ending in the defeat of the Spanish and the annexation of Puerto Rico, Guam and the Phillipines.

To get even with the support given to Cuba, the U.S. presented The Platt amendment which stated that

Cuba could make no treaties without U.S. agreement. Cuba could not create indebtedness beyond its
means to pay. The U.S. reserved the right to intervene in Cuba to maintain law and order.The U.S. was granted rights to a naval base at Guantanamo Bay until 1999, which they still run. (COMPLETE CONTROL OVER THE CUBAN POLITICAL LIFE, NO NEED FOR ANNEXATION)

The whithe's men thought to Christianize and educate inferior people

The “open door policy” which stated that the Chinese empire had to remain whole, united and under Chinese control.  China would be open to US trade and missionaries, opposing European colonialism and supporting the opening of foreign markets.

• Opposing colonialism and fostering open markets would domiante U.S. Foreign policy into the XXI century.

In 1903, President Theodore Roosevelt helps Panamanians revolt against Colombia, seizing for the U.S. a 10 mile wide area through Panama. They began building an isthmian canal which opened in 1914., allowing access to U.S. ships both in the Atlantic and the Pacific. (CONTROL OVER THE SEAS AND CENTRAL-SOUTH AMERICA)

Over the next several decades, until Presidents Hoover and Franklin Roosevelt pursued a “good neighbor” policy, the United States continued to intervene in Latin America.

And so, how did The United States of America evolved from the old and distroyed empire the Civil War led, into the new powerful and interventionist empire that was just described?

•The nation's economic approach to foreign affairs,empowered by the risign economic powers inside the country due to the Industrial Revolution, led to an overseas sight. They were so optimistic about the reborned nation and the positive impact of the Industrial Revolution, economy was rising and they started to buy new territories (Expansionism).
• The growth of the Navy and army during the Civil war made the American military much more powerful, with batallions ready to itnervene in the continent and outside of the continent, examples: American- Spanish War (Cuba, Philipines, Puerto Rico)

• The establishment of clear ideals and principles in its approach to other nations: Open door policy with
China, support for the Panama Canal Project via doctrines such as the Monroe Doctrine (and its influence on Latin America), economic expansionism (with its investments in foreign lands –Cuba) and its continuous belief in the Manifest Destiny.

And that is how the great power we see today began. They settled values that they still carryon today, and having such congruence between their political speech and the actions taken is what keeps The United States as the ruling nation.

Never the less, the speed of the establishment of all this policies make me think about conspiracies, I mean, It took less than a decade to run all this operations and expansion their power as they did.