The paprticipation of Blacks in the Union Army was a key element in the Union victory.
The period before the outbreak of the Civil War was one of the most tense in American history. There was an intense struggle between the leaders of the North and South over who would control the destiny of the country. The southerners wished to extend slavery into the new territories and states while the Northerners wanted those same areas to be free of slaves. They wanted the new states to be part of the growing northern industrial empire. The growth of industry was not as well suited to slavery as the largely agricultural economy which the southerners wanted to expand. In addition to this economic cause of tension, there was a widespread humanitarian movement in the North which called for the abolition of slavery (as well as the guarantee of women’s rights) on moral grounds.