Slavery was not a major issue until the middle of the 19th century. "In 1854, the Kansas-Nebraska Act, sponsored by Democrat Stephen A. Douglas, brought slavery to the forefront of national attention" (Leidner, Gordon, 2009).
Some states like South Carolina tried to skirt the issue of slavery by seceding from the Union, thus creating a cascading effect on other states. By the time the Civil War began on 12 April, 1861, seven states had seceded from the Union.
There was a great deal of emotion. The opposing sides had differences that could have been resolved without going to war. However, the United States was a new nation and also a very big nation. Differences of opinion on critical issues such as the presidency as well as slavery brutally tested each side. Also, there were powerful leaders on both sides whose aggressive positions kindled war rhetoric.
Apart from emotions, there were also reasons of economy and propriety. The issues may also have been those of political expediency. "The 1854 Kansas-Nebraska Act sponsored by the Democrat Stephen A. Douglas brought slavery to the forefront of national attention" (Leidner, Gordon, 2009). Under this act, slavery could be introduced anywhere in the United States under popular will. The Kansas-Nebraska Act created a firestorm in the North where slavery was not approved. Abraham Lincoln opposed Stephen A. Douglas.
One thing led to another. Verbal attacks and legislations led to release of pent-up frustrations and anger. A shot fired by South Carolina on Fort Sumter, a symbol of federal authority, started the Civil War (Abraham Lincoln).
To what extent did Abraham Lincoln oppose slavery
According to Abraham Lincoln, "slavery was the opposite of opportunity and mobility" (Abraham Lincoln). Lincoln voiced his opposition to slavery although he did not wish to abolish slavery by force in states where it existed. He was of the opinion that slavery will constitutionally exit wherever it existed in the United States through industrialization and the will of the people. He did not feel it necessary to go to war to abolish slavery.
Nonetheless, the Kansas-Nebraska Act was a retrograde step in the wrong direction and Lincoln was alarmed. He was concerned it was only a matter of time for the Act to take effect and continue to bolster slavery rather than limit and ultimately eliminate it. Having become president, Lincoln initially tried to deal with the issue diplomatically and reconcile with the seven states that had seceded (Abraham Lincoln). He was not successful. There were hard feelings in the south. They were ready for war in support of slavery. In the circumstances, there was no alternative other than declaration of war.
Could a compromise of some kind have prevented the war or was it inevitable
There was no room for compromise. There was no way anybody could have compromised with the Kansas-Nebraska Act. The purpose of this Act was to extend slavery rather than limit and abolish it. It allowed racism to continue and grow.