Political tensions over slavery seemed to fade after the Missouri Compromise in 1820. With the commencement of the War with Mexico in 1846, however, fresh conflicts erupted. Many Northerners felt that the South was seeking land from Mexico in order to expand slavery. The North also refused to consider any extension of slavery into new states once it was established here. These differences led to a split in the Democratic Party, with Northern Democrats forming their own organization known as the Republican Party.
During the Civil War (1861-65), the Union Army captured slaves owned by individuals it found along the road south of Vicksburg. President Abraham Lincoln issued an executive order on March 3, 1862, prohibiting the further capture of slaves by the army and authorizing commanders to give freedom to any slave they found working on Confederate land or property. This order applied only to areas under Union control at the time it was issued. In May 1863, Congress passed a joint resolution calling for the termination of all forms of slavery within the Confederacy. However, the resolution included no mechanism for implementing this provision, so it had little effect on reality. In fact, many Southerners viewed slavery as an integral part of their society and were unwilling to give it up without a fight.
In the post-bellum era, former slaves sought compensation from Southern landowners for lost labor.
When a result, as the United States gained more territory during the nineteenth century, the argument over slavery was pushed to the center of American politics. Missouri petitioned to join the Union as a slave state for the first time in 1820. A heated dispute occurred, but the Missouri Compromise was finally reached. This agreement allowed Missouri to enter the Union as a slave state and Nebraska as a free state. This compromise satisfied neither side, so no state entered the union at that time with either property rights or slavery banned.
After the Louisiana Purchase by France in 1803, it became clear that there were large areas of land along the Mississippi River that could be settled by slaves. Many Southern plantation owners saw this as an invasion of their territory that would allow blacks to escape from South Carolina to Illinois. They objected strongly to this scheme called "manumission." In addition, many Americans in other parts of the country felt that slavery should be allowed into new states. This issue came to a head in Congress where representatives from both sides of the argument had to agree on any legislation. No agreement could be reached, so Congress did nothing significant to address manumission or slavery in general.
As more states joined the Union, the balance of power between North and South shifted toward the former. By the end of the Civil War in 1865, every state except Missouri had abolished slavery.
In the meantime, several attempts were made to bring about a gradual abolition of slavery.
The Missouri Compromise, often known as the 1820 Compromise, was an agreement between pro- and anti-slavery groups to regulate slavery in the western territories. It outlawed slavery in new states north of the Arkansas territory's boundary, except Missouri. The agreement was proposed by Senator Henry Clay (Kentucky) and supported by President James Monroe.
In Congress, the opponents of slavery used their power as a majority to block all attempts at legislation concerning slavery. So management of this issue fell to the states. As more states ratified the Constitution, slavery became entrenched as part of American life. The number of slaves rose steadily until the Civil War ended slavery nationwide.
The Missouri Compromise was intended to avoid the dissolution of the Union over the issue of slavery. In the south, it is called the "dominion doctrine" because it provided for federal regulation of slavery in the territories. This prevented violence between northern and southern states over slavery. New states could decide for themselves whether to allow slavery, but it could not be allowed in those that had already formed part of the union for five years. This compromise also ensured that Missouri would become a slave state, helping maintain stability in the South.
These were the main elements in the Missouri Compromise.