About Lincoln. I don't mean to contradict you, but I've heard the other side of the Lincoln medallion too.
He inherited a crisis from Buchanan, but didn't he worsen it by using the military against states that had every right to leave the Union?
There had been some level of crisis for years, but the main event to trigger the secession was simply Lincoln being elected. The Republicans were clearly an anti-slavery party, and the South saw writing on the wall. Lame duck Buchanan did sit by passively.
Did the states have the right to leave the Union? Lincoln didn't think so. His position was that the states owe their existence to the formation of the nation, and thus can't leave the union without the consent or agreement of the national government. Was he right? That will be debated endlessly. But as Lincoln said, secession was "an issue which can only be tried by war and decided by victory." The war largely settled the question as a practical matter. Not to say that might makes right, but the Union's was effort would not have been successful without the support of most of the US population, and the vast majority of Americans since have considered the nation to be preeminent over the states.
And overwhelmingly right? Wasn't his use of the military proven unconstitutional?
By "right" I was referring mostly to his decisions for winning the war, which I didn't make clear. But the war began with secessionist military forces attacking Federal installations and seizing Federal property, that is, property that belonged to all the states. So its pretty easy to justify using the military constitutionally under the powers of commander-in-chief.
Truman ignored what was going on in China, and didn't put a lot of pressure on Chiang. Truman threw money at the problem but didn't get involved.
Put pressure on Chiang to do what? The numbers were clearly against him, and experience in the war had proved the KMT almost hopelessly corrupt. And how would you suggest Truman "get involved?" The US had just finished fighting a huge and costly war, and a new war against China would probably have been worse than Vietnam, Iraq and Afghanistan combined. Truman's containment policy was followed to one degree or another by all successive presidents, Republican and Democrat. "Truman lost China" was more a McCarthy-ite slogan than a realistic political criticism.
Wilson sent a huge army force into Russia to free the Czechs. They nearly succeeded in overthrowing the Reds but by the time they got that close, WWI was coming to an end and Wilson gave up.
The US forces in Russia (Siberia and Archangel) numbered less than 20,000 and had about a zero chance of overthrowing anything, and that was not their mission anyway. The logistics issues were atrocious, as were the Siberian operating conditions. And if you're suggesting large-scale US involvement in Russia, I would say that would have been disastrous: (A) Fighting for one side of a civil war historically doesn't work out too well for a third party, and (b) Russia has a home-field advantage that you don't want to mess with.
--Justin