For the united states, the lesson learned from the vietnam war was that

powers  are  denied  to the  national governmentin three distinct ways: some  powers, such as the  power  to levy duties on exports or prohibit the freedom of religion, speech, press, or assembly, are expressly  denied  to the  national government  in the  constitution.

the anwser is missions

answer; (c) slaves brought to the americans from africa;