Even after the South surrendered, in 1865, the aftermath of the war saw intense resentment that, it is said, continued even until after the last veteran of that war finally died of old age.

Perhaps the most famous civil war in history began on April 12, 1861, when secessionist Southerners attacked the United States Army garrison at Fort Sumter, South Carolina. Subsequent hostilities embroiled the American states in bloody battles that slaughtered a large portion of their youthful male population. About a quarter of each army was killed and nearly half a million wounded, many of them grievously.

What could cause such brutal fratricide?

While officially, the Civil War was not fought over the issue of slavery, there can be little doubt that without the existence of legalized slavery, matters would have been very different and, perhaps, even peaceably resolved.

Slavery was a condition over which, despite legislated compromises since 1789 and beyond, no permanent compromise was possible. There was, and is, no middle ground. Human rights are what they are, and those rights are a central principle in the Declaration of Independence and the United States Constitution. Reasonable disagreements over general human rights may arise concerning limits and specifics, but as to the central issue, there can be no doubt: it is abominable for one man to own another, as one owns cattle or land.

Today, with the issue of slavery settled and sealed in blood, it seems inconceivable that the United States might ever again engage in such mutual mass slaughter. What could possibly cause it?

Consider abortion. It either is or is not the violation of the right of an unborn child to live.

Consider the so-called gender issues. Either homosexuality (along with so-called transgenderism) is worthy of the full protections of the law (as in, for example, redefining marriage to include same-sex couples), or it is not. Opposition is considered by some to be the intentional infliction of suffering upon gays and transgenders.

There are more issues than these two that divide Americans irreconcilably, but they might top the list at the moment. And irreconcilable they are.

"Abortion rights" began with a misguided interpretation of a right to privacy, the right of a pregnant woman to exercise the power of life and death over her unborn child during the first trimester of gestation. From that beginning, it has expanded ever farther, to include so-called late-term abortion. Virginia's Governor Ralph Northam's hideous description of infanticide outside the womb, which he tacitly endorsed as a proposed law, is far beyond any possibility of compromise. Opponents of abortion are accused of being anti-woman.

So-called gay rights began with a plea from homosexuals to be free from harassment, but over time, the concept has infringed more and more on religious liberties, and the right of free speech, of others. Policies now in place in certain locales require that everyone speak as if he believed that if a man claims to be a woman, he is one. "Mis-gendering" someone — that is, by calling a woman a woman when she identifies as being a man — is already, in some cases, cause to be fired from one's job, possibly sued in court, and eventually to be imprisoned once the movement runs its course. High school children can be required to shower with members of the opposite sex.

Gender issues include such amorphous topics as toxic masculinity, a concept that is beginning to suggest that laws be made forcing parents to raise their children as "gender fluid" or lose custody. Public schools propagandize small children into points of view held by transgender advocates, with no practicable "opt out" provision for parents who object, nor any mention of opposing points of view, except pejoratively.

Statements like these bring charges of fear-mongering, just as a few years ago, the specter of same-sex "marriage" was scorned by gay rights advocates as propaganda.

Where are the public debates over these issues? On what college campus is it permitted to openly declare unpopular opinions on these matters without physical violence being used to suppress dissident speakers?

How many more divisive issues will result in the infringement of rights and in violent protests? Global warming? Public displays of Christian crosses? Assisted suicide and involuntary euthanasia? Racial reparations? Sharia law? Illegal immigration? How many? How far will the violence go? When will the rage break us apart?

What does it take to start a civil war? Where is today's version of Fort Sumter?