The united states entered world war ii after the japanese attack on pearl harbor.

After the Pearl Harbor attack, and for the first time during years of discussion and debate, the American people were united in their determination to go to war. Three days later, Japan's allies Germany and Italy declared war against the United States.

Explanation:

I hope this will help

regarding the law, the 15th amendment was specifically designed thinking in the rights of black free men.

even though ratified on february 3, 1870, the promise of the 15th amendment would not be fully applied for a long time.poll taxes and literacy tests would allow southern states disenfranchise african americans. only in 1965 the voting rights for african americans would be actually able to vote in the south.

in 1965, president johnson signed the voting rights act, which aimed to overcome legal barriers that prevented african americans from voting as it was guaranteed by the 15th amendment to the u.s. constitution.