Between Lincoln being elected, the Emancipation Proclamation being formed through slaves fighting in the war, it was all a struggle for political power over people, government and law.
In 1860 Lincoln was elected for the first time. When he was elected the south, later known as the Confederacy, seceded from the Union. The Confederates slowly took over forts still loyal to the Union, that were located in the south. The reason they did this is because Lincoln was a threat to slavery, which was the main source of there economy.
Lincoln tried to save as many forts as he could, but in the end it was useless. If he sent supplies they would be attacked and start a war. If he didn't the forts would die. In the Lincoln couldn't leave his men behind without supplies. He sent supplies to fort Sumter, the supplies never made It. War was declared on the Confederacy in April of 1861.
In January of 1863 Lincoln Declared the Emancipation Proclamation. The proclamation freed all slaves in rebel, or confederate, territory. It still left the slaves loyal to the union slaves though. Not all free southern slaves could escape the south. Only slaves that were close to the borders could get away. So most of the freed slaves were also to far from Union soldiers to be saved.
This proclamation was not used so he could free all slaves. He simply used it to weaken the south so he could have a better chance. This gave Lincoln an upper hand in winning the war. This proclamation let African American freed slaves fight in the war.
As soon as the emancipation Proclamation was made African Americans poured in to fight in the war. The most known regiment was the 54th of Massachusetts. They trained the hardest. They went with out pay. They were one of the first African American regiments. The regiment had two sons of Fredrick Douglass. In 1863 they led the Attack on Fort Wagner. This battle made them how famous they are now. Every time African Americans fought they faced graver danger than white soldiers. Instead on being held prisoners when captured they were returned to slavery or killed.
In essence the Civil War was primarily a political struggle. Between Lincoln being elected. The Emancipation proclamation being formed. To slaves fighting in the war. It was all a struggle for political power over people, government and law.