By the end of the Civil War, more than African Americans had joined the Union army.

By the end of the war more than 186,000 black soldiers had joined the Union army

Explanation:

On March 6, 1863, the Secretary of War was informed that "seven hundred and fifty blacks who were waiting for an opportunity to join the Union Army had been rescued from slavery under the leadership of Harriet Ross Tubman" By the end of the war more than 186,000 black soldiers had joined the Union army; 93,000 from the Confederate states, 40,000 from the border slave states, and 53,000 from the free states.

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b) the confederacy had to pay all union war expenses.

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