After Abraham Lincoln signed the Emancipation Proclamation on January 1, 1863, and slowly but surely transformed the scale and meaning of the Civil War, most Americans then understood what the President had done better than most Americans do now. Those who hated and opposed any emancipation doubted the enactment’s long-term constitutionality and accused the President of launching a “social revolution” with dire consequences for race relations and the South’s way of life. For those favoring emancipation, some argued that it was a long-delayed act of national morality, while many more said it was the best way to weaken Southern society, destroy the Confederacy, and therefore win the war. They were all right.

Among the many insights in Louis P. Masur’s Lincoln’s Hundred Days is how well wartime Americans, elites and common folk alike, understood emancipation even as they struggled to imagine the future it would create. They were, after all, living the daily nightmare of increasingly all-out civil war. “War is a realist,” Ralph Waldo Emerson wrote in his journals, “shatters everything flimsy & shifty, sets aside all false issues, & breaks through all that is not real as itself.” The prospect of emancipation in a war caused by slavery suddenly focused the mind. From the earliest months of the conflict, Masur writes, “discussions of emancipation saturated newspaper columns, lecture halls, and Congress.” And they did so in the language of “military necessity”—that is, slavery had to be destroyed as a means of defeating the confederacy and preserving the Union. As Masur demonstrates, “the doctrine of military necessity” became both slogan and strategy on the lips of soldiers and civilians alike much earlier and more ubiquitously than many historians may have realized. The idea was certainly not Lincoln’s invention, though his name eventually became forever attached to it.

This tale has been told so many times, so many ways—by Lincoln’s worshippers, by his haters, and by many careful scholars. The story of Lincoln the emancipator is at heart one of a moderate, pragmatic, anti-slavery politician who instinctively and ideologically preferred gradualism, who did not believe whites and blacks had a future of genuine equality in America, and who—driven by events in the greatest crisis of national existence—committed some extraordinarily radical acts. But why might his contemporaries have grasped and explained the Emancipation Proclamation and its immediate consequences better than most people can today?

Such dissonance exists not because historians have failed to provide enough to read about Lincoln, but because in our strained and contested historical memory, in our lore, we need our Lincoln pure—the moral man in an immoral world assuring us we can be better. This impulse helps explain, in part, the popularity of Steven Spielberg’s Lincoln. Is it because the American slaves were liberated in such overwhelming bloodshed that we need to see a genius-captain at the helm of the ship of national destiny, lest we admit that we destroyed ourselves in the Civil War before trying to create ourselves again? Or is it because the Proclamation itself, and the equally important Thirteenth Amendment that followed in 1865, are such dull, legalistic documents, so deeply embedded in constitutionalism, that we continue to insist that they are more profound and meaningful than they sound? Solemn public readings of the Emancipation Proclamation are almost always about the present in which they are performed and rarely about any original context. Myth so often trumps reality and we cannot prevent it.

In the Civil War years, Americans could watch the President grow in stature and change his ideology, especially in relation to slavery. But if we want to keep our Lincoln purer for today’s uses, even if admirably pragmatic and a bit corrupt, we can follow along with Spielberg and screenwriter Tony Kushner as they give us the evolved abolitionist Lincoln of the last few months of the war, and not the hesitating, racially ambivalent leader of 1861-62. No one will make that movie. Brilliant as he was as the Lincoln of early 1865, Daniel Day-Lewis would have encountered a more challenging role if he had portrayed the pre-September 1862 Lincoln. Often in books, and surely in the movies, we choose the Lincoln we need.

By 1862—as the war expanded across the American landscape, casualties rose to ghastly levels, and defeating the Confederacy demanded new imagination—Lincoln became consumed with the problem of emancipation. Masur, who teaches history at Rutgers University, is especially effective at charting this emerging imperative in both Lincoln’s presidency and his personal character. Beginning in the fall of 1861, in his first entreaties to the four nonseceded border slave states of Maryland, Delaware, Kentucky, and Missouri, Lincoln made it clear that his preferred approach to ending slavery was to find the least revolutionary and most lawful methods to erode and ultimately abolish it. He proposed variations on gradual, compensated emancipation (owners would be paid for their legal property), with as many freed blacks as possible “voluntarily” removed from the United States in numerous schemes of “colonization,” many of them organized by the Lincoln Administration itself.

On March 6, 1862, Lincoln drafted a message to Congress urging “pecuniary aid” to any state willing to “adopt gradual abolishment” of slavery. Cautious with every step, he suggested this plan as the “initiation of emancipation,” hoping for a legal, willful process that in the end no border state accepted. Congress would begin to push ahead of him with a compensated emancipation act for the District of Columbia in April and, after long and embittered debate, the Second Confiscation Act in July, which authorized the freeing of the slaves of all disloyal owners in the Confederate states, as well as any who escaped to Union lines. Lincoln signed both acts into law, as he also began work on the executive order of his own. With abolitionists attacking him for acting so cautiously, and pro-slavery Democrats howling against emancipation, Lincoln, as Masur shows, suffered emotionally under barrages of criticism from all sides. But in the wake of the Battle of Antietam, as Robert E. Lee’s Confederate army had to retreat from its pivotal invasion of Maryland, Lincoln issued his Preliminary Emancipation Proclamation on September 22, 1862.

That document was effectively a warning, a first draft for all the world to digest, telling the Confederates that unless they ceased their rebellion, slaves in their states would be freed on January 1, 1863, and the stakes of the war escalated to the revolutionary levels that most on both sides had hoped would never come. In the Preliminary Proclamation, and especially in his Annual Message to Congress in December 1862, Lincoln argued aggressively for gradual, compensated emancipation by the Southern states themselves, and for continued plans for colonization of blacks within North America or outside the continent. Lincoln’s famously measured style, his capacity to present himself sometimes on both sides of the question, stimulated opposite reactions then, as it has ever since. His secretary, John Hay, referred to Lincoln’s caution as “dignified reticence.” But Frederick Douglass, while finding his own ways to shoulder up to Lincoln’s “hesitating” approach to emancipation, nevertheless hated the persistent demand for colonization. The black abolitionist considered colonization an insult to the humanity and birthright of African Americans. When Lincoln in August 1862 lectured a small delegation of handpicked black ministers about how the presence of blacks had caused the war and then tried to recruit them to lead schemes of colonization to the coal-producing regions of Central America, Douglass exploded in disgust. The President was “silly and ridiculous” toward his guests, and blaming blacks for the conflict was “like a horse thief pleading that the existence of the horse is the reason for his theft.” After Lincoln’s prolonged appeal for colonization and gradualism in the Annual Message, Douglass accused him of “crudeness” and “feebleness,” and even called him “demented.”

Lincoln’s prudence is so often portrayed as his genius for reading public opinion, his steady progress toward a more aggressive position as he constantly tested the political winds. All this has much validity. Sometimes, though, we must remember that, as Lincoln readily admitted, he reacted to events as much as he controlled them. As Masur nicely shows, Lincoln usually explained himself in homespun stories, drawn from frontier wisdom. When pressed at one point by exasperated anti-slavery congressmen about his caution on slavery, he responded by telling a tale about a group of traveling Methodist ministers in Illinois. A river was up ahead, and “the waters was up. And they got considerin’ and discussin’ how they should git across it, and they talked about it for two hours, and one on ’em thought they had ought to cross one way when they got there, and another another way, and they got quarrellin’ about it, till at last an old brother put in, and he says, says he, ‘Brethren, this here talk ain’t no use. I never cross a river until I come to it.’”

Exasperation with Lincoln among abolitionists eroded, if never fully ceased, after he signed the final Proclamation. The famous document reads largely like a legal brief, with several uses of “whereas,” “therefore,” and “hereby.” Lincoln called emancipation “a fit and necessary war measure for suppressing said rebellion,” and he devoted a full paragraph to naming the states still in rebellion, as well as the exceptions of 13 parishes of Louisiana and 48 counties of Virginia (which became the state of West Virginia) where Union forces had occupied the territory. Widely anticipated and debated across the country, the Proclamation was distributed and read aloud among troops at the warfront, in contraband camps of refugee freedmen, and in formal celebrations in Northern cities. In its immediate moment, the legalistic language—so written in anticipation of endless court challenges by former slaveholders once the war ended—was hardly the issue.

In two crucial ways the final Proclamation was different from the first document issued 100 days earlier. It abandoned any open effort for colonization, and it authorized the recruitment of black troops into the Union Army. Lincoln acted under his powers as commander in chief. Emancipation was to be a weapon wielded against an enemy, a means of making and winning a war. He authorized the seizure of the human property of the Confederacy, on the perpetual bondage of whom secession and war had been launched. It was Lincoln’s legal way of saying that the American republic, in order to survive and revive, had to crush the South’s revolutionary movement for a slaveholders’ republic. He had indeed launched a social revolution by military means.

Although the Proclamation freed slaves only in the “states in rebellion,” exempting the border states as well as regions under Union military control, it now meant that if the North could ultimately win the war, every forward step of the Union Army and Navy was a liberating step for the slaves, for Lincoln himself, and for the whole nation. The Proclamation said nothing about the status or rights of those freed slaves, although it did urge them to “abstain from all violence” and “labor faithfully for reasonable wages,” suggesting that in such liberation by the sword a new history had begun. Douglass knew this as he embraced the final Proclamation, began recruiting black soldiers, and declared his faith that Lincoln would never turn back on his promise. “We are all liberated by this Proclamation,” Douglass announced in February 1863. “Everybody is liberated. The white man is liberated, the black man is liberated, the brave men now fighting the battles of their country against rebels and traitors are now liberated.”

Indeed, the remarkable discovery for many readers of Masur’s book may be that so many white Northerners, trapped in a national and personal existential crisis, wanted such liberation. They surely wanted to win the war; now they began to see they could not do so without freeing slaves. What they once might never have voted for, they now wished for. Racists became abolitionists almost overnight. “We like the Negro no better now than we did then,” wrote an Illinois captain from the front, “but we hate his master worse and I tell you when Old Abe carries out his Proclamation he kills this Rebellion and not before. I am thenceforth an Abolitionist and I intend to practice what I preach.”

This one soldier’s odd eloquence sums up two generations of modern scholarship on emancipation. As policy and process, the Emancipation Proclamation was a morale booster in the Union army. It is striking how Masur found so many common Yankee soldiers’ diaries and letters that referred to Lincoln in such endearing terms as “Old Abe” or “Uncle Abe.” Many wrote as though he—the President—had given them a heightened reason to fight. On December 28, 1862, an Iowa private wrote home in dire need of hope after the terrible Union defeat at Fredericksburg: “We are all looking anxiously for the 1st of January and the workings of Old Abe’s proclamation. We all feel that it will end the war and that it is the only thing that will give us a chance of seeing our homes very soon since Burnside’s defeat on the Rappahannock.”

Intellectuals and leaders of all sorts also understood what Lincoln initiated. Responding to the Preliminary Proclamation, anti-slavery governor John Andrew of Massachusetts called it “a poor document, but a mighty act; slow, somewhat halting, wrong in its delay till January, but grand and sublime after all.” Harriet Beecher Stowe captured Lincoln’s intent nicely and accurately: “Come in, and emancipate peaceably with compensation; stay out, and I emancipate, nor will I protect you from the consequences.” And, observing with great interest from England, Karl Marx astutely described Lincoln’s style and substance. “Lincoln,” wrote Marx, “is a sui generis figure in the annals of history….He gives his most important actions always the most commonplace form…[like] routine summonses sent by a lawyer to the lawyer of the opposing party….[T]he manifesto abolishing slavery is the most important document in American history…tantamount to tearing up the old American Constitution.” Many scholars today tend to interpret the Proclamation in ways similar to these famous contemporaries of Lincoln’s—with a kind of nuanced triumphalism. The general public, meanwhile, tends to demand a more flattened, uncomplicated, and triumphal memory of Lincoln’s greatest act.

Masur has a great eye for the telling passage and has conducted splendid research, especially into this matter of the Proclamation’s reception and meaning among Northerners (though he too often lets documents speak for themselves at great length, burdening his narrative with excessively long block quotations). The book is not merely about the one hundred days between September 1862 and January 1863; it’s really about the famous document’s causes and consequences within the full scope of the war.

Masur does not fawn at Lincoln’s feet as some scholars do, especially on emancipation; the book is no hagiography, and the author does not shy away from the sensitive issue of Lincoln’s persistent interest in colonization, which has been a kind of scholarly family embarrassment, too easily avoided at times over the generations of Lincoln biographies. He does state his interpretation of Lincoln clearly, if a bit softly. Masur shows us a Lincoln who was “no gambler,” who feared failing at this high-stakes brand of making history. He considers Lincoln’s legendary caution a supreme virtue, and we see the President in several moments of genuine depression and personal suffering, if not outright uncertainty. But Masur might have risen from his sources for a moment and probed a bit further into the depths of the great man’s pained ambivalences, especially on race and the future of the new nation this horrible war was about to produce.

And Masur misses some opportunities to interpret Lincoln’s words and contexts to illuminate our own political times. The beleaguered President’s brilliant use of the idea of “liberty” at a Sanitary Fair in Baltimore in 1864 is provocatively relevant to our own agonized uses of that keyword today. “We all declare for liberty,” said Lincoln, “but in using the same word we do not all mean the same thing. With some the word liberty may mean for each man to do as he pleases with himself, and the product of his labor; while with others the same word may mean for some men to do as they please with other men, and the product of other men’s labor. Here are two not only different, but incompatible things, called by the same name—liberty.” Why did Masur not link that to today’s Tea Party politicians squawking about the government’s assault on their “liberty,” even as liberals stay silent about an American keyword they have allowed the right wing to own?

What Masur has written is a biography of a document in the rich contexts of its emergence, explained by the very people who had to carry out and live with its imperatives. He helps the reader grasp why and how the Proclamation became an executive order, although he might have interpreted more deeply the lasting significance of this “stroke of the pen” for the history of race and presidential power in America. He lets his sources elucidate this great transformation of history as much as he offers commentary of his own. Confounding modern attitudes, he shows us how the idea of freeing slaves as “military necessity” possessed its own moral meaning to those who died to save a reimagined Union. And though Lincoln was a master of timing, Masur’s diversity and depth of sources demonstrate that the besieged President both “led and responded to” events he never fully controlled. The image of the wily, conniving, duplicitous puppeteer, ingeniously ushering the national church to its new civil religion of freedom and equality, while laced with half-truths, ought to remain the stuff of legend rather than history. But legends are often much more enduring than even the best of historical interpretations, and Masur might have told us more about why that is so.

Lincoln’s presidency, especially his handling of emancipation, does offer a kind of seminar on the arts of pragmatism. No leader ever earned the genuine sadness in his face and soul any more than Lincoln. And he grew enormously from the colonizer in chief of 1861-62 to the abolitionist in chief of the Second Inaugural in 1865. Perhaps no one captured this element of Lincoln’s character and leadership better than W.E.B. Du Bois, who in 1922 declared of the sixteenth President: “I love him, not because he was perfect, but because he was not and yet triumphed….The world is full of folk whose taste was educated in the gutter. The world is full of people born hating and despising their fellows. To these I love to say: See this man. He was one of you and yet became Abraham Lincoln.” To Du Bois, Lincoln, like the nation itself, was the embodiment of paradox, and it is that which drew him to the “sad-faced” leader. “There was something left, so that at the crisis he was big enough to be inconsistent—cruel, merciful; peace-loving, a fighter; despising Negroes and letting them fight and vote; protecting slavery, and freeing slaves. He was a man—a big, inconsistent, brave man.” From such stuff of myth and history, Du Bois left one of the most enduringly honest descriptions of Lincoln ever written. In our polarized political culture today, and with our limited attention spans and desire for shorthand history, we would do well to remember Lincoln and emancipation through such a lens of paradox and unfinished beauty.