Iraq is in the running for the biggest mistake in US history? I have a one word rebuttal to that sentence. Slavery.

I'm sure we can find a lot of things more horrible than Iraq. Like slavery as you say, or bombing Hiroshima and Nagasaki, or the war in Vietnam...

But what I think OP meant, is that the bad things which happened in Iraq were not the intended outcome of what the US did. Those other, more horrible things were intended consequences, not mistakes.

I'll agree that slavery was worse than the invasion of Iraq, but I wouldn't call it a "mistake".

Not quite sure why. Some tries:

1. A mistake implies a single decision.

2. Slavery worked as intended, right? It was more evil than mistaken.

Either way, you sure derailed my derailing of the topic, so I'll stop here :)

Calling slavery a mistake is very... mild. It should have its own category

I think mistake implies good intentions.

Also, it's very strange that you can imply The United States started a war with good intentions with a straight face.

I always think of mistake as simply "to be wrong". Am I mistaken in my assumption?

Kind of, yes. If you're wrong intentionally, we have all sorts of other words for that, including trolling, propaganda, misdirection, incitement, lying, fraud, perjury, all of which have their own connotations for your intent. We wouldn't really call any of those situations a "mistake".

Not only did we try, but we did it the wrong way imo. When you try to pull something this complex off and completely disregard the local culture, politics, and sectarian makeup, you introduce chaos. Did anyone learn from Sykes-Picot?