Final answer:
Abraham Lincoln's role during the Civil War was President of the United States (Union). He played a vital role in leading the Union and making decisions to preserve the Union and end slavery.
Step-by-step explanation:
Abraham Lincoln's role during the Civil War was B. President of the United States (Union). He served as the 16th President of the United States from 1861 to 1865, and his presidency coincided with the Civil War. Lincoln played a crucial role in leading the Union during this challenging time, making key decisions and implementing policies to preserve the Union and abolish slavery.
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