Ah Joe, we've actually had a few violent periods. The War for Independence, the War of 1812, the Mexican American War, and the worst and most costly in American history, and the last on our own soil, the War Between the States. I hate calling it the Civil War, as war is anything but civil. More accurately put, it should be called the unCivil War.
This is a good read on the latter subject:
http://books.google.com/books?id=JB0...+war+chronicle
And some folks forget that Lincoln was the first Republican President, and while he was in office, is when America became embroiled in it's bloodiest war ever.