After the end of the Civil War in 1865, American would not experience an international war until

Until Spanish-American war that was fought in 1898.

Explanation:

After Civil War United States started rearranging their internal, but also external policy. At the end of 19th Century United States started spreading their power outside their country. During that period in 1898 a war was waged against Spain. Known as the Spanish-American war it was fought around Cuba and Philippines. United States remained a world power.

because it !

its main object was the establishment of "settlement houses" in poor urban areas, in which volunteer middle-class "settlement workers" would live, hoping to share knowledge and culture with, and alleviate the poverty of, their low-income neighbors.