Final answer:
Efforts to eradicate slavery took place during the U.S. Civil War, and the 13th Amendment was passed to abolish slavery.
Step-by-step explanation:
The efforts to eradicate slavery took place during the U.S. Civil War. The amendment that was passed during the Civil War and abolished slavery was the 13th Amendment, which was ratified in December 1865. The 13th Amendment outlawed slavery and involuntary servitude in the United States, effectively ending the institution of slavery.