Abraham Lincoln was born into a very poor family, but he later become one of the most important【D1】______of the United States. In 1860, he was elected to become the 16th president of the United States, mainly because of his opposition to【D2】______By that time, most【D3】______states had abolished slavery, but the agricultural states in the【D4】______still wanted slaves to work on their plantations. After Lincoln’s election, southern states began to secede(break away)from the United States. They based their secession on a doctrine called " states’rights, " which gives citizens of individual states the power to nullify(overturn)federal laws. After Lincoln’s inauguration in 1861, he urged all sections of the United States(the Union)to remain united. He used all his powers to avoid a civil war, but his efforts【D5】______. On April 12, 1861 , the war began with the bombardment of a Union fort, Fort Sumter, South【D6】______ By the middle of the【D7】______War, President Lincoln concluded that the nation could never exist as half-slave and【D8】______He issued the【D9】______Proclamation, which freed the slaves in the Confederate states. In 1865, the Union soldiers defeated the Confederate soldiers and the war ended on April 9, 【D10】______.

【D8】().