The Republicans were obliged to make anti-slavery the main focus of their political ideology due to political reasons and the Northern society. The fact that many abolitionists supported the Republican Party is an indication that anti-slavery formed a big party of the Republican ideology. It was one of the few policies which united the republican factions. Most politicians agreed that slavery was the major issue of the decade between 1850 and 1860. The Douglas Democrats believed that the South had embarked upon a crusade to force slavery into all territories, and protested that approval of that goal would destroy the northern Democracy. For their part, southerners insisted they would not accept popular sovereignty since this would be as effective as the Wilmot Proviso in barring slavery from the territories.
Anti-slavery was an abstract feeling that long existed in the North. Politicians of all parties agreed that northerners opposed slavery as a principle, although they disagreed on the intensity of the feeling. George William Curtis stated, “the moral mixture in this feeling was abstract support, hatred for the slaveholders, jealousy for white labor, and the little amount of consciousness of wrong done and the wish to correct it.”
Most Republicans were united under by the principles of free soil and unionism. It is said that many Republicans were anti-slavery from the idea that slavery threatened the Union. Still Unionism was only one aspect of the Republican ideology. The integrity of the Union was important to the national greatness Republicans felt the United States was destined to achieve.. Resentment of the southern political power, devotion to the Union, antislavery based upon the free labor argument, moral revulsion to the peculiar institution, racial prejudice, a commitment to the northern society, its development and expansion were all associated in the Republican ideology.
This republican ideology led to the secession of the South from the Union, a failure of its ideology of Unionism. As Southerners viewed the Republican Party’s rise to power in one northern state after another, and witnessed increasingly anti-southern tone, they felt hostile in the same way. The people of the North and of the South came to hate each other worse than the hatred between two nations in the world. The South also feared that a Republican administration would adopt a program of indirect action against slavery. North and South both knew that the election of Lincoln in 1860 had marked a turning point in the history of slavery in the United States. To remain in the Union, the South would have had to abandon its entire ideology of slavery. Thus secession was a logical response by the South to the situation. It may now be stated that the single cause of the American Civil War was slavery.