The subject of the great compromise was how the congress would deal with legislation. It was a debate whether the states should be equally represented, or should they be represented based on the size of the state, that is, on the size of the population. The decision was to have a compromise and have a bicameral government where both systems would be implemented in the best interest of all states with the senate having equal representation, and the house having population representation.
They decided that for now slavery would be legitimate and legal, but in the future the Congress would decide the future of slavery in the country. The 3/5ths compromise was important in this because of how slaves would account for during census when it comes to representation. In the future however we know what the congress did and how slavery was first forbidden in the North, and then later in the south as well.
The U.S did not join the League of Nations following WWI. Even the the President of the United States at that time, Woodrow Wilson, was enthusiastic about the organization, they didn't officially join it. The reason why they didn't join it was because of isolationists in congress, in other words, people that didn't agree with what other people are interested in. Because of the war and all of the fatal deaths of Americans, people didn't want the U.S to be affiliated with Europe in any way.
Sun Yat-sen is the known father of modern china.
Economic sanctions and military force