Answer:
<u><em>William H. Seward</em></u>
Explanation:
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Answer: Slavery became a national issue because it split the country into two groups due to each state's beliefs on slavery. To be more specific, the Southern states were pro-slavery, and the Northern states were anti-slavery. This caused a civil war between the two groups, which made Abraham Lincoln, the president at the time, abolish slavery.
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