Let their last feeble and lingering glance rather behold the gorgeous ensign of the Republic, now known and honored throughout the earth, still full high advanced, its arms and trophies streaming in their original luster, not a stripe erased or polluted, nor a single star obscured, bearing for its motto no such miserable interrogatory as, “What is all this worth?” nor those other words of delusion and folly, “Liberty first and Union afterward”; but everywhere, spread all over in characters of living light, blazing on all its ample folds, as they float over the sea and over the land, and in every wind under the whole heavens, that other sentiment, dear to every true American heart—Liberty and Union, now and for ever, one and inseparable!
Daniel Webster, 3/7/1850 (during the South Carolina secession crisis):
I wish to speak to-day, not as a Massachusetts man, nor as a Northern man, but as an American, and a member of the Senate of the United States. It is fortunate that there is a Senate of the United States; a body not yet moved from its propriety, not lost to a just sense of its own dignity and its own high responsibilities, and a body to which the country looks, with confidence, for wise, moderate, patriotic, and healing counsels.Thomas Hart Benton and pistols in the Senate
You want polarization? Here's some polarization. Representative Preston Brooks of South Carolina beats Senator Charles Sumner of Massachusetts
Lincoln-Douglas debate (24:32)
Congress and the Civil War
The Lincoln movie and parliamentary procedure
The Lincoln movie, more generally...
The congressional oath of office dates from this era.
Background on the impeachment process.
There is an entire site on the Johnson impeachment.