What were two of Frederick Douglass’s major contributions to the Civil War?

He encouraged President Lincoln to make the emancipation of slaves the primary aim of the war.
He met with the president to discuss equal pay for black soldiers.
He made it possible for African Americans to buy plantations in the South.
He actively supported the recruitment of African Americans in the Union army.
He set up the American Red Cross to treat wounded African American soldiers.

These were the two reasons:

He actively supported the recruitment of African Americans in the Union army.

He encouraged President Lincoln to make the emancipation of slaves the primary aim of the war.

Explanation:

The contribution of Frederick Douglass at the time of the Civil war has been signification in terms of modern discourse about the war and what it has essentially become for the people in the modern time.

This is a suggestion from Douglass himself who wanted Lincoln to maintain that slavery is the primary reason of the war.

He also wanted the enlisting of the black population into the army so that they can fight for the freedom of their own brethren and also inspire the ones in south.

he was sent to prison on various charges for protesting south africa's policies of apartheid