As plans for President Donald Trump’s big military parade are slowly beginning to take shape, it is worthwhile recalling an incident that occurred during the biggest military parade in U.S. history—the Grand Review of the Armies in May 1865 at the end of the U.S. Civil War—which may have impacted the subsequent role of the U.S. military in American politics and society.

As the victorious 60,000-strong Armies of the Tennessee and Georgia, commanded by eccentric and willful Gen. William Tecumseh Sherman, marched down Pennsylvania Avenue on the second day of the colossal military spectacle on May 24, onlookers were not merely interested in the battle-hardened, rough-looking soldiers that had smashed Confederate forces in the West and cut a path of destruction through Georgia and the Carolinas. Rather, they were anxiously awaiting what would happen when Sherman met U.S. Secretary of War Edwin Stanton on the reviewing stand.

Recommended: The 5 Biggest Nuclear Bomb Tests (From All 6 Nuclear Powers).

Recommended: How Israel Takes U.S. Weapons and Makes Them Better.

Recommended: North Korea’s Most Lethal Weapon Isn’t Nukes.

As many contemporary observers noted, once Sherman reached the reviewing stand, he dismounted and went up the platform to greet the dignitaries, including U.S. President Andrew Johnson and his old friend Ulysses S. Grant, the commanding general of all U.S. forces. The historian William Marvel in his book Lincoln’s Autocrat: The Life of Edwin Stanton recounts what happened next:

[W]hen a hopeful Stanton extended his hand Sherman let him grasp the air with it, clapping his own hand to his side and merely nodding or bowing slightly. Across the avenue sat others who had been waiting for this very moment, many of whom had trained binoculars or opera glasses on the tall, florid general and the squat, grey bureaucrat.

One observer noted: “Sherman’s face was scarlet, and his red hair seemed to stand on end.” Julia, the wife of Ulysses S. Grant wrote: “What a defiant and angry glance he shot at Stanton.”

Sherman proudly recalled in later life: “As I approached Mr. Stanton, he offered me his hand, but I declined it publicly and the fact was universally noticed.” Rumors even circulated after the parade that Sherman had called Stanton “nothing but a damned clerk”, which, however, turned out to be false.

What had caused this public rift between one of the Union’s most respected generals and an iconic member of Lincoln’s wartime government on a day dedicated to celebrating the end of a war that killed over 750,000 Americans and that the former called “the happiest and most satisfactory moment of my life”?

The short answer: bruised egos and personal ambitions. Among other things, Stanton thought Sherman was fishing for the “Copperhead nomination for President.” A longer exposé, nonetheless, would need to emphasize the secretary of war’s (unfounded) fear of a military takeover of the government in 1865 by an officer who may have become too powerful as a result of the conflict to be reined in by civilian authorities. In April 1865, Stanton was the driving force in convincing the government and the North’s public that Sherman had overstepped his authority when he negotiated a surrender agreement with Confederate Gen. Joseph E. Johnston in North Carolina, directly accusing him of insubordination and indirectly—via leaks to the press of government bulletins—of treason. The results were predictable. Sherman felt publicly humiliated, willfully maligned and double-crossed by Stanton.

The disagreement between the two provides an excellent case study of a crisis in civil-military relations in nineteenth-century America. In an e-mail exchange, Richard H. Kohn, offers a notional definition of such a crisis broadly dividing it into two categories: “First is the defiance of orders, or knowing insubordination. Second is one of exceeding one’s authority as a senior military officer that causes real political or other difficulty or crisis.” The Sherman-Stanton rift touches both categories. According to Stanton and other politicians, Sherman knowingly defied orders and caused real political difficulties to the administration as is shown below.

Stanton: The Dick Cheney of His Day

That such a civil-military skirmish would involve Edwin Stanton is not surprising. Stanton, whom the historian William Marvel called the “Dick Cheney of the Lincoln Administration,” was seen as Lincoln’s power hungry and autocratic lieutenant. Although successfully reforming the War Department, including curtailing rampant corruption and boasting superb organizational skills, he was careful to husband his own personal influence and authority under the guise of the military necessity to expand the federal government’s reach in wartime.

For example, it was primarily Stanton who persuaded the Lincoln cabinet to seize extra constitutional powers including suspending habeas corpus and the power to make extraordinary arrests without due process. He also took military possession of telegraph lines to exert control over the North’s media and, in a revealing episode to sideline military leadership, removed the telegraph line from Army Headquarters and installed it in the War Department, which prevented the commanding general (George McClellan at the time) from directly communicating with the White House.

It was also Stanton who unilaterally decided to try the Lincoln assassination conspirators in military court behind closed doors despite stiff public opposition. This was partially based on his conviction that the Confederate government in Richmond was involved in the killing of the U.S. president. Yet, he also had personal reasons for wanting to be seen as tough on the South: He sought to ingratiate himself with Radical Republicans committed to an extreme form of Reconstruction, as well as to the incumbent U.S. president Andrew Johnson, who initially sought to inflict a severe punishment on the South for the rebellion (Johnson would later reverse course).

In many ways, the cantankerous but shrewd political operative Stanton was the antidote to the egocentric yet upright soldier Sherman. Indeed, the fast-talking general, always a bundle of nervous energy, was open in his disdain of politics and politicians, although one of his brothers served as a U.S. senator. When asked later whether he would stand as the Republican candidate for president, Sherman barked: “I will not accept if nominated and will not serve if elected.” What Stanton and Sherman shared, however, was a ruthlessness when opposed, paired with an oversensitivity to criticism, often culminating in a take-no prisoners attitude when challenged. Both were also prone to hyperbole.

Johnston’ Surrender

Following the surrender of Robert E. Lee’s Confederate Army of Northern Virginia to Ulysses S. Grant at Appomattox Court House on April 9, 1865, the only remaining large Confederate force in the Eastern theater of operations was under the command of Joseph E. Johnston encamped in North Carolina facing Union armies under Sherman. On April 17 and 18, Johnston and Sherman negotiated an intricate surrender convention based on the terms Grant conceded to Lee at Appomattox and which Sherman had called “magnanimous and liberal.” They were joined by Confederate secretary of war John Breckinridge.

Although, in a letter to Grant vouching that he would “be careful not to complicate any point of civil policy,” Sherman, in his draft, in the words of William Marvel “proposed nothing less than a blueprint for Reconstruction, including a general amnesty, the restoration of citizens’ political rights, and the preservation of state governments.” Sherman claimed to have acted in the spirit of Abraham Lincoln: “Recalling the conversation of Mr. Lincoln at City Point [where Lincoln vaguely promoted a policy of leniency to the South], I sat down at the table and wrote off the terms, which I thought concisely expressed this views and wishes, and explained that I was willing to submit these terms to the new President.”

As James Lee McDonough in his biography of Sherman notes:

He had entered into terms of a political nature. His document recognized the existing state governments in the South, effective as soon as their members took an oath of allegiance to the United States. (…) His terms sanctioned the reestablishment of Federal courts in the South, and guaranteed “the political rights and franchises” of the Southern people, “as well as their rights of persons and property.” The terms seemed even to leave a possibility of recognizing the Confederate war debt. Sherman also indicated that no one was to be punished “by reason of the late war, so long as they live in peace and quiet.”

Interestingly, the document did not specifically address the issue of slavery, although Sherman said that Johnston and Breckinridge “admitted that slavery was dead.” He also noted that he “could not insist on embracing it in such a paper, because it can be made with the states in detail.” His major concern, Sherman later wrote, was to prevent the breakup of Rebel forces into guerilla bands. Nevertheless, the agreement Sherman sent for presidential approval to Washington on April 18 outlined the postwar status of seceded states. In short, Sherman had negotiated a full-blown peace treaty with the Confederacy—vicariously usurping both congressional and presidential powers.

Upon reviewing the agreement, Grant advised Stanton and President Johnson to immediately summon an emergency cabinet meeting to discuss the terms. Stanton repeatedly insinuated to cabinet members that Sherman’s action did not merely constitute insubordination—but treason. The cabinet rejected the agreement with the U.S. president now also calling Sherman an outright traitor. Stanton “waxed especially vitriolic on Sherman,” according to Marvel. “Stanton reacted as if Sherman had penned an unalterable treaty rather than a proposal to be duly considered,” McDonough writes. Ron Chernow in his book, Grant, notes that the secretary of war seized the opportunity to pursue a vendetta against Sherman and “turn him into a public pariah.” Grant harshly called Stanton’s actions “that inexplicable and cruel storm of defamation.”