Tariff
A tariff is called an optimal tariff if it's set to maximize the welfare of the country imposing the tariff. It is a tariff derived by the intersection between the "trade indifference curve" of that country and the offer curve of another country. In this case, the welfare of the other country grows worse simultaneously, thus the policy is a kind of "beggar thy neighbor policy". If the offer curve of the other country is a line through the origin point, the original country is in the "condition of a small country", so any tariff worsens the welfare of the original country.
Tariff in United States history
The American Civil War (1861-1865) was partially fought over the issue of tariffs. The agrarian interests of the South were opposed to any protection, while the manufacturing interests of the North wanted to maintain it. The fledgling Republican Party led by Abraham Lincoln, who called himself a "Henry Clay tariff Whig", strongly opposed free trade, and implemented a 44-percent tariff during the Civil War—in part to pay for railroad subsidies and for the war effort, and to protect favored industries. In 1847, he declared: ""Give us a protective tariff, and we shall have the greatest nation on earth"".