The president states that this act of justice" is being done upon military necessity ." What did Abraham Lincoln mean by this statement?

Still, Lincoln's Emancipation Proclamation that began as a “matter of military necessity” marked the beginning of an “Act of Justice” by the President as he pursued full constitutional sanction to end the inexorably unconscionable institution of the forced unpaid servitude of black people held as slaves.

answer; /// i believe that the correct answer is( it left behind rich

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