Final answer:
The biography of Abraham Lincoln predominantly covers his presidential leadership through the Civil War, including his views on slavery and the Union.
Step-by-step explanation:
The main topic covered in the biography of Abraham Lincoln is his leadership during one of the most tumultuous times in American history: the Civil War. The biography details his early life, his rise in politics, his election as the 16th president, and his efforts to preserve the Union. One of the most pivotal aspects of his presidency was his stance on slavery, which evolved over time, resulting in the Emancipation Proclamation in 1863, declaring freedom for slaves within the Confederacy. The biography also touches on Lincoln's initiation of the Reconstruction and his views towards extending voting rights to African American Union Army veterans before his assassination in 1865.
In his first inaugural address, Lincoln emphasized the permanent nature of the Union and made a plea for reconciliation between the northern and southern states, even as tensions mounted around the issue of slavery and states' rights that would soon erupt into the Civil War.