America is celebrating putting the British Empire on notice with the Declaration of Independence 249 years ago. But the document that cemented the union in 1776 also infused President Lincoln with the moral authority to save it “four score and seven years” later. 

Unlike the Constitution, the Declaration isn’t a governing document. It’s a statement of America’s principles — and grievances against the British crown that are long since moot — rendered with such elegance that they fulfilled far more than their original purpose.

A testament to the power of President Jefferson’s language was what happened when President Washington read it at Lower Manhattan on July 9, 1776. At what is now City Hall Park and was then the Commons, soldiers, civilians, and Sons of Liberty assembled to hear the patriot case for war.

Washington wasn’t a fiery orator, yet his recitation whipped the crowd into a mob that stormed to Bowling Green Park and pulled down King George III’s statue. For a document beginning, “We hold these truths to be self-evident,” meaning obvious, it kindled something new: the American spirit.

In 1861, when Lincoln was inaugurated, several states had already left the union. America faced an unprecedented challenge that was, as Lincoln said at Gettysburg in 1864, “testing whether” a nation “conceived in liberty” could “long endure.”

Lincoln knew he needed more than guns and grapeshot to crush the rebellion. He had to tell the nation, as Washington had at the Commons, why its cause was just. The Constitution — silent on the matter of states leaving the union — was a poor fit for that mission.

To build the rallying cry he needed, Lincoln reached back to the Declaration, which he’d done in his campaign for the Senate. On August 17, 1858, at Lewiston, Illinois, he confronted those who might be finding the secessionist argument appealing. 

Lincoln addressed his “countrymen” who’d been “taught doctrines conflicting with the great landmarks of the Declaration of Independence.” He then urged them to reject “suggestions which would take away from its grandeur and mutilate” its meaning. 

“If,” Lincoln said, “you have been inclined to believe that all men are not created equal in those inalienable rights enumerated by our chart of liberty, let me entreat you to come back. Return to the fountain whose waters spring close by the blood of the Revolution.”

A demagogue might have claimed Jefferson’s words as an endorsement, but not Lincoln. “Think nothing of me,” he said, or “the political fate of any man whomsoever, but come back to the truths that are in the Declaration of Independence.” 

“You may do anything with me you choose,” Lincoln said, “if you will but heed these sacred principles.” The crowd “may defeat me for the Senate” or “put me to death,” but he and his opponent, Senator Douglas, were “nothing” held against the Declaration.

“Do not destroy,” Lincoln said, “that immortal emblem of humanity.” Douglas won the Senate race, but Lincoln beat him and two others for the presidency two years later and arrived in Washington with his pitch for the union ready.

In an address to Congress on his first Independence Day as president, Lincoln again invoked the Declaration against the secessionists. He noted that the “United Colonies” had not declared “their independence of one another or of the Union, but directly the contrary.”

The original 13 colonies, and those that joined later, had made a “mutual pledge” to one another. Lincoln added that two years later, the Articles of Confederation were “conclusive” in their statement that “the union shall be perpetual.”

The 13 members of the Confederacy, Lincoln said, had “never been states, either in substance or in name, outside of the union. He asked where “this magical omnipotence of ‘state rights,’ had come from, asserting a claim of power to lawfully destroy the union itself.” 

From Congress to Gettysburg, Lincoln made the Declaration of Independence central to his rhetorical defense of the union. It was a document written in 1776. But thanks to its transcendent principles and stirring themes, it not only began the American experiment. It helped save it, too.