Final answer:
Frederick Douglass used his influence as an activist and his popular newspaper to convince Lincoln to allow Black men to serve in the military.
Step-by-step explanation:
The individual who used his influence as an activist and his popular newspaper to help convince Lincoln to allow Black men to serve in the military was Frederick Douglass. Douglass was a renowned abolitionist and social reformer who played a significant role in the fight for African American rights. Through his writings and speeches, he strongly advocated for the inclusion of Black men in the military during the American Civil War.
Learn more about Frederick Douglass and activism