What were the causes/origins of world war i?

What principle did president truman invoke in sending u.s. troops into south korea without first asking congress to declare war?

What does the quote describe? “the closeness of the place, and the heat of the climate, added to the number in the ship, which was so crowded that each had scarcely room to turn himself, almost suffocated us….the shrieks of the women, and the groans of the dying, rendered the whole a scene of horror almost inconceivable.”

How did women contribute to the success of the american revolution