Link: https://slatestarcodex.com/2019/09/04/list-of-passages-i-highlighted-in-my-copy-of-ages-of-discord/

Turchin has some great stories about unity vs. polarization over time. For example in the 1940s, unity became such a "problem" that concerned citizens demanded more partisanship:

Concerned about electoral torpor and meaningless political debate, the American Political Science Association in 1946 appointed a committee to examine the role of parties in the American system. Four years later, the committee published a lengthy (and alarmed) report calling for the return of ideologically distinct and powerful political parties. Parties ought to stand for distinct sets of politics, the political scientists urged. Voters should be presented with clear choices.

I have vague memories of similar demands in the early '90s; everyone was complaining that the parties were exactly the same and the "elites" were rigging things to make sure we didn't have any real choices.

On the other hand, partisanship during the Civil War was pretty intense:

Another indicator of growing intraelite conflict was the increasing incidence of violence and threatened violence in Congress, which reached a peak during the 1850s. The brutal caning that Representative Preston Brooks of South Carolina gave to Senator Charles Sumner of Massachusetts on the Senate floor in 1856 is the best known such episode, but it was not the only one. In 1842, after Representative Thomas Arnold of Tennessee "reprimanded a pro-slavery member of his own party, two Southern Democrats stalked towards him, at least of one of whom was arhmed with a bowie knife…calling Arnold a 'damned coward,' his angry colleagues threatened to cut his throat 'from ear to ear'" (Freeman 2011). According to Senator Hammond, "The only persons who do not have a revolver and a knife are those who have two revolvers" (quoted in Potter 1976:389). During a debate in 1850, Senator Henry Foote of Mississippi pulled a pistol on Senator Thomas Hart Benton of Missouri (Freeman 2011).

In another bitter debate, a New York congressman inadvertently dropped a pistol (it fell out of his pocket), and this almost precipitated a general shootout on the floor of Congress (Potter 1976: 389).

358. Hero or Villain: Episode 5 - Josip Tito