But Johnston anticipated this maneuver and withdrew his forces to a position behind the Rappahannock, forcing McClellan to improvise. When Union forces eventually surveyed the evacuated Confederate position at Manassas, they found modest defenses, not the impenetrable fortress McClellan feared. “The fancied impregnability of the position turns out to be a sham,” a newspaper correspondent wrote. “Utterly dispirited, ashamed, and humiliated,” wrote another reporter, “I return from this visit to the rebel stronghold, feeling that their retreat is our defeat.”

McClellan’s new plan was a landing and assault on the peninsula formed by the York and James rivers. He pulled off the logistics. But when half of his army approached rebel defenses near Yorktown, Va., he hesitated. McClellan believed he was at a disadvantage, if not outnumbered. In reality, his 55,000 men greatly outnumbered the roughly 13,000 Confederate defenders. Lincoln urged him to attack and warned that with “delay the enemy will relatively gain upon you.” But a wary McClellan opted for an artillery siege instead.

This pattern would repeat itself over the course of the campaign, with McClellan overestimating Confederate strength and opening his armies up to attack and defeat. At the Battle of Seven Pines outside of Richmond, Union armies sustained heavy casualties but successfully repelled a rebel assault. Unnerved by the experience, McClellan settled in for a siege of the capital rather than press his advantage. Now led by General Robert E. Lee, Confederate armies fortified defenses around Richmond and counterattacked, ultimately breaking McClellan’s will to fight. The Union commander withdrew to a base on the James River before returning to Washington on Lincoln’s command. A potential strategic breakthrough had become a bona fide defeat that would prolong an already brutal war.

The way I see it, the Democrats are roughly in McClellan’s position. With the House of Representatives in hand, they have the power and authority to aggressively check the president’s behavior. Voters, who cast a vote against Trump as much as they did for a Democratic majority, may not expect it, but it’s hard to think they would oppose it. And Trump is unpopular, with a 42 percent approval rating despite presiding over strong economic growth.

Democrats have the upper hand, but they aren’t acting like it. Yes, they have taken action against the president — that’s why he has fought to stymie their investigations. But the logic of their arguments and accusations leads to impeachment, and there, they have flinched, worried that the public — or at least Republican voters — will rally to his side. Instead of a direct confrontation using everything at their disposal, Democrats want to maneuver around the president as if there’s another path to victory.

But there isn’t. The next election will be about Trump. His base, as well as most Republican voters, will almost certainly be with him. What Democrats need is the confidence of their position. At this stage, when most Americans say they won’t vote for Trump in 2020, they have the public. They have evidence of wrongdoing. They have all the tools they need to seize the initiative and center the next year of political conflict on the president’s contempt for the Constitution and the welfare of the American people.

On April 9, 1862, an agitated Lincoln sent McClellan a telegram, urging him to move against Confederate defenses. “I beg to assure you that I have never written you, or spoken to you, in greater kindness of feeling than now, nor with a fuller purpose to sustain you, so far as in my most anxious judgment, I consistently can. But you must act.” McClellan refused, the Confederacy claimed the field, and the Union paid the price.