The Republican Party, which fielded its first candidate in 1856, was opposed to the expansion of slavery. Abraham Lincoln, the party's nominee in 1860, was seen as a moderate on slavery, but Southerners feared that his election would lead to its demise, and vowed to leave the Union if he was elected.
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D.Members of an alliance had to defend each other if one went to war.
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Why did some believe that US expansion was needed to preserve the "American Spirit?" They thought that America would need a strong navy to protect the markets. Also, in Alfred Mahan's book, The Influence of Sea Power Upon History, he says that America's future would rely on gaining new markets abroad.
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