Do you remember when Donald Trump promised to “unify” the nation? Do you recall the many times he said he would be everyone’s president?

I do. It was just four years ago. It seems like an eternity.

Here we are. We’re on the cusp of another presidential election. My several social media networks are abuzz with memes, proclamations, hysteria. Donald Trump’s re-election effort has produced — at least in my memory — the most hateful back/forth possible.

Why is that? How did we get to this point?

I have to point straight, with both hands at the White House, at the guy who lives there with his wife and youngest son. Donald Trump has failed to deliver on many of his 2016 presidential campaign promises.

The “unity” pledge stands out. It’s a doozy. Trump’s strategy has been clear almost since the day he took the oath of office: He would speak only to his base; the rest of us, especially those who voted for his opponent four years ago, do not matter to him.

The result has been hate speech disguised as “political discourse.”

I’ll be clear: We have been through more divisive times in this country; the Civil War comes to mind; so does the Vietnam War; Watergate, too.

In my lifetime, though, this era — ushered in with the election of a first-time office seeker and former reality TV show host — has been unique in the level of hostility between the sides. Friendships have been plowed asunder. Family members are at each others’ throats. Prominent politicians have quit talking to those on “the other side of the aisle.”

Why is that? I focus my attention and the blame at the man at the top of the heap, the current president of the United States.

Donald Trump occupies the bulliest of political pulpits imaginable. The president is fully capable, were he so wired, to guide the tone of the debate toward a civil tone. Instead, Donald Trump has used that pulpit to foment the anger that has devolved into hatred.

This is my statement of fair warning that we need to prepare ourselves for the gutter-level campaign that Donald Trump intends to produce for us. This won’t be fun.