In his new study of Abraham Lincoln’s wartime leadership, Tried by War, the eminent historian James McPherson writes, “In the vast literature on our sixteenth president…the amount of attention devoted to his role as commander-in-chief is disproportionately far less than the actual time that he spent on that task.” Indeed, in the sea of Lincoln books, there are by my count only four that examine his performance as war president—this, for “the only president in American history whose entire administration was bounded by war.”

The dearth of works devoted to Lincoln’s wartime leadership is doubly strange, McPherson observes, since the success or failure of Union arms during the Civil War affected

the fate of slavery; the definition of freedom; the destruction of the Old South’s socio-economic system and the triumph of entrepreneurial free-labor capitalism as the national norm;…the origins of a new system of race relations; the very survival of the United States in a manner that laid the foundations for the nation’s emergence as a world power.

Lincoln was entering uncharted waters as he confronted a rebellion “too powerful to be suppressed by the ordinary course of judicial proceedings.” In response to this crisis, as Geoffrey Perret observed in Lincoln’s War (2004), the sixteenth president “create[d] the role of commander in chief.” Claiming broad emergency powers that he argued the Constitution had vested in the executive branch, he called out the militia, authorized increases in the size of the regular army and navy, expended funds for military purchases, deployed military forces, blockaded Southern ports, suspended the writ of habeas corpus in certain areas, authorized arbitrary arrests, and empanelled military tribunals to try civilians in occupied or contested areas. He took these steps without congressional authorization, although he subsequently explained his action to Congress once it convened in July 1861. Later he authorized conscription and issued the Emancipation Proclamation.

Lincoln justified these steps as necessary to save the Union and preserve the Constitution. As he famously wrote to Horace Greeley:

I would save the Union. I would save it the shortest way under the Constitution. The sooner the national authority can be restored, the nearer the Union will be “the Union as it was.” …My paramount object in this struggle is to save the Union, and it is not either to save or to destroy slavery. If I could save the Union without freeing any slave, I would do it, and if I could save it by freeing all the slaves, I would do it; and if I could save it by freeing some and leaving others alone I would also do that.

But this often misunderstood passage conceals an important point: for Lincoln, the Union and the Constitution that he sought to save were not ends in themselves but the means to something else. He saw the Constitution principally as a framework for sharing power within a republican government. This was the real thing he aimed to preserve because only republican government was capable of protecting the liberty of the people. He understood the Declaration of Independence as the foundation of such a government, and the Constitution as the means of implementing it. To achieve the end of preserving republican liberty, he had to choose the means necessary and proper under the circumstances and it is by his end and his choice of means that we must judge Lincoln’s claim of a war power, the balance he struck between liberty and security, his response to secession, his decision for emancipation, and the strategy he employed to fight the war.

Executive Prerogative

Don Fehrenbacher once observed that Lincoln has been described by historians as a “dictator” far more often than any other president. This is true not only of historians who criticize him, but of those who praise him. But if Lincoln was a dictator, he was unlike any other in history. Dictatorship (in the contemporary usage that Fehrenbacher had in mind) is characterized by unlimited, absolute power, exercised in an arbitrary and unpredictable manner, with no regard for political legitimacy. A dictator does not go out of his way to respect legal limits as Lincoln did, despite his belief that the emergency required special measures. Nor is a dictator subject to the pressures of public opinion, congressional constraint, and party competition that Lincoln faced during his war presidency. Above all a dictator doesn’t risk an election, especially one he thinks he might lose, in the midst of civil war.

Lincoln argued that the power he needed to deal with the rebellion was found in the Constitution, in the executive power. In addition to the Commander-in-Chief Clause, he cited the clause of Article II requiring him to “take care that the laws be faithfully executed,” and his presidential oath to “preserve, protect, and defend the Constitution of the United States.” He emphasized as well the difference between normal times and times of extraordinary emergency. During the former, the rights of the people are secure and the main instrument of representative government is the legislature, which expresses the will of the people. During such times, the president, though he possesses his own constitutional source of power, primarily executes the laws passed by Congress. But in a crisis, the principle salus populi est suprema lex trumps all other considerations and justifies extraordinary executive powers. As Thomas Jefferson observed, “in times of peace the people look most to their representatives; but in war, to the executive solely…to give the proper direction to their affairs, with a confidence as auspicious as it is well-founded.”

This executive prerogative is rendered necessary by the fact that laws arising from legislative deliberation cannot foresee every exigency. For the safety of the republic, the executive must retain some latitude for action. Here, again, is Jefferson on the spirit of the prerogative:

A strict observance of the written law is doubtless one of the high duties of a good citizen, but it is not the highest. The laws of necessity, of self preservation, of saving our country when in danger, are of higher obligation. To lose our country by a scrupulous adherence to written law, would be to lose the law itself, with life, liberty, property and all those who are enjoying them with us; thus absurdly sacrificing the ends to the means….

After Fort Sumter, Lincoln made the same point in his speech to Congress in special session, in defense of his suspension of the writ of habeas corpus:

The whole of the laws which were required to be faithfully executed were being resisted and failing of execution in nearly one third of the States. Must they be allowed to finally fail of execution, even had it been perfectly clear that by the use of the means necessary to their execution some single law, made in such extreme tenderness of the citizen’s liberty that, practically, it relieves more of the guilty than of the innocent, should to a very limited extent be violated? To state the question more directly, are all the laws but one to go unexecuted, and the government itself to go to pieces lest that one be violated? Even in such a case, would not the official oath be broken if the government should be overthrown, when it was believed that disregarding the single law would tend to preserve it?

Lincoln did not believe he had violated the law because the privilege of the writ of habeas corpus may be suspended, according to the Constitution, “when, in cases of rebellion or invasion, the public safety may require it.” But he made it perfectly clear that he, or any president, must be willing to violate some part of the law if that is necessary to save the whole of it.

Emergency Power

Of course, an emergency power is useless unless it is sufficient to meet the emergency. The magnitude and the character of the emergency determine the extent of the necessary power, and the president is in the best position, Lincoln believed, to determine how much power he needs. But Lincoln’s emphasis on preserving republican government taught him, as it should teach us, that the prerogative is limited by the will of the people, which,

constitutionally expressed, is the ultimate law for all. If they should deliberately resolve to have immediate peace, even at the loss of their country and their liberty, I know not the power or the right to resist them. It is their own business, and they must do as they please with their own.

He was certain that he had constitutional authority to exercise extraordinary powers in an emergency, and he was equally certain that such powers were limited to the duration of the emergency and not applicable to normal times. He articulated his position with characteristic, down to earth rigor in his reply to Erastus Corning and a group of New York Democrats who had criticized his war measures:

I can no more be persuaded that the Government can constitutionally take no strong measures in time of rebellion, because it can be shown that the same could not be lawfully taken in time of peace, than I can be persuaded that a particular drug is not good medicine for a sick man because it can be shown to not be good food for a well one. Nor am I able to appreciate the danger apprehended by the meeting [of the New York Democrats], that the American people will by means of military arrests during the rebellion lose the right of public discussion, the liberty of speech and the press, the law of evidence, trial by jury, and habeas corpus, throughout the indefinite peaceful future which I trust lies before them, any more than I am able to believe that a man could contract so strong an appetite for emetics during temporary illness as to persist in feeding upon them during the remainder of his healthful life.

Lincoln faced other dilemmas as war president. One was the dual nature of the conflict: it was both a war and a domestic insurrection. Believing that the states could not legally secede and that, therefore, the Confederacy was a fiction, he had to be careful lest the steps he took be construed as recognizing the Confederacy. His decision to blockade Southern ports, traditionally a measure taken against a belligerent, might be so construed. So might confiscation of rebel slaves, however attractive the practice might be. Lincoln’s concerns about the constitutionality of the two confiscation acts passed by Congress and the fact that they implied recognition of the Confederacy led him to treat emancipation as a war measure. The mere fact that he was morally in favor of emancipation could be no justification for him as president to use the force of government to bring it about.On the surface, Lincoln seemed ill-prepared to meet the military challenges that the crisis of the Civil War generated. By all ordinary measures, the Confederate president, Jefferson Davis, would seem to have had the edge. He was a graduate of the U.S. Military Academy at West Point, had a distinguished record during the Mexican War, had been secretary of war during the administration of Franklin Pierce, and as a United States senator from Mississippi had chaired the Committee on Military Affairs. In contrast, Lincoln had served as a captain of militia during the Black Hawk War, during which he had seen no action. His one term in Congress was lackluster. He gained notoriety for opposing the Mexican War, as did most Whigs, and for demanding of President James Polk that he show the very spot upon which Mexico supposedly had provoked the conflict.

War Leader

Some have concluded that appearances are not misleading and that Lincoln’s contributions to Union victory were minimal. Given the relative power of the North, according to this interpretation, Union victory was assured beforehand; Lincoln’s role was superfluous at best, and at worst his propensity for interfering in the details of military operations was counterproductive. A variation of this view holds that Lincoln’s main contribution to Union victory was to find the right general, wading through a mass of incompetents until he lit upon Ulysses S. Grant, who led the Union armies to success.

In recent years, some historians have begun to give Lincoln more credit as a war leader. He demonstrated flexibility and strategic acumen. He skillfully managed both his cabinet and his generals, and even Congress, where he had to maintain a working majority if the war was to be won. He did not hesitate to overrule his advisers, both military and civilian. As Eliot Cohen noted in Supreme Command (2002), his study of civil-military relations in modern republics, “Lincoln had not merely a powerful intellect but an extraordinarily orderly and balanced one.” The Union’s material advantage was not sufficient in itself to ensure victory. Lincoln had to make the decisions that translated this advantage into military and political success.

We sometimes forget that he also had to defeat the strategy pursued by the Confederacy. And certainly with field commanders as talented as Robert E. Lee, Confederate armies did confound Union plans on more than one occasion.

The Union Strategy

Although Lincoln had no military education, he learned quickly and proved to be a competent strategist. He abided by the old adage that in war, “the main thing is to make sure that the main thing remains the main thing.” As his letter to Horace Greeley illustrated, the “main thing” for Lincoln was to preserve the Union. But like any good strategist, Lincoln proved willing to adapt his strategy to the circumstances in order to achieve this goal.

He intuitively understood that it was not the capture of Confederate territory or the Confederate capital that would bestow victory. To break the back of the rebellion required Union armies to defeat Confederate armies. “I think Lee’s army and not Richmond, is your true objective point,” he wrote to Major General Joseph Hooker in June 1863.

Despite the understandable tendency of both sides to concentrate on the eastern theater of war, Lincoln understood the importance of the West in Union strategy. In early 1862, Union armies had employed the Tennessee River as the “main line of operations” to penetrate deep into western Tennessee and northern Mississippi, turning Confederate defenses on the Mississippi River and in Kentucky. Grant’s subsequent victory at Shiloh permitted Union forces to seize major parts of the Confederacy’s only remaining east-west railroad line and opened the way to both Vicksburg on the Mississippi River and Chattanooga. With the capture of the latter, Union forces penetrated the Appalachian barrier and seized Atlanta.

Of course there was a great deal more to Lincoln’s strategy than the military element. His was also a political strategy, the main weapon of which became at the end of 1862 emancipation. Emancipation struck not only at the war-making potential of the Confederacy but at the heart of the Southern social system. Nonetheless, Lincoln had to tread carefully for domestic political reasons because, while abolitionists and their radical Republican allies in Congress welcomed emancipation, conservative Democrats in the North and loyal slaveholders in the slave states that remained in the Union denounced it. Lincoln needed both groups if he was to prosecute the war.

The president’s preferred approach to ending slavery, as Allen Guelzo argues in his Lincoln’s Emancipation Proclamation (2004), was gradual, compensated emancipation. But this scheme required acceptance by the loyal slave states and military success. Neither came to pass. The Emancipation Proclamation was Lincoln’s response to the failure of Union arms and of compensated emancipation. The time had come, as he wrote to Cuthbert Bullitt, to stop waging war “with elder-stalk squirts, charged with rose water.”

The stronger medicine represented by the Emancipation Proclamation was necessary because the Confederacy was just now exerting maximum effort to mobilize its population for war. In April 1862, the Confederate congress passed a conscription act and organized its mobilized manpower into field armies. One of these, the Army of the Mississippi, struck Grant at Shiloh. Lee’s Army of Northern Virginia drove General McClellan back from the gates of Richmond. Then in the fall of 1862, the Army of the Mississippi invaded Kentucky and Lee invaded Maryland. To a great extent, the South was able to do this only because slave labor freed white men to fight. Emancipation could undermine the slave labor system of the South, thereby undercutting the Confederate effort to mobilize its military resources.

From a military standpoint, emancipation was a war measure designed to attack the Southern economy directly. As slaves came under control of Union forces, they could be substituted for soldiers who were required to labor, freeing them up to fight. Thus emancipation had the effect of transferring labor from South to North, increasing the fighting potential of Union armies while decreasing that of the Confederate armies.

Militarily, the Emancipation Proclamation opened the way to the next logical step in this process of weakening the South while strengthening the North: enrolling blacks as soldiers in the Union army. The manpower boon to the Union was substantial. Some 180,000 black soldiers served in the Union army. They constituted 120 infantry regiments, 12 regiments of heavy artillery, 10 batteries of light artillery, and seven cavalry regiments. At the end of the war, they constituted 12% of the Union’s military manpower.

Although the material contribution of African-Americans, both freedmen and former slaves, to Union victory was substantial, their participation in the war to achieve their own liberty was important for its own sake. Without their participation, the war to save the Union as it was could not have been transformed into a war to save the Union as it should be,” i.e., without slavery, and it is unlikely that African-Americans could ever have achieved full citizenship and equality in the United States.

Lincoln and His Generals

Eliot Cohen has shown that Lincoln’s presidency is by no means a model of the so-called “normal” theory of civil-military relations, according to which the civilian authority establishes the goals of the war and then steps out of the way to permit the generals to implement what they believe to be the best military measures to achieve those goals. Lincoln was an activist commander-in-chief who frequently “interfered” with his generals by constantly asking questions and goading them to perform more aggressively.

Early in the war, Lincoln faced a severe crisis in civil-military relations in the person of Major General George McClellan, the commander of the Union Army of the Potomac. Historians tend to treat McClellan as a first-rate organizer, equipper, and trainer but an incompetent general who was constantly outfought and outgeneraled by his Confederate counterpart, Robert E. Lee. But this is a serious misreading of the situation Lincoln faced. McClellan was not incompetent. On the contrary, he and many of his favored subordinates disagreed with Lincoln’s policies, and indeed may have attempted to sabotage them. McClellan pursued the war he wanted to fight—one that would end in a negotiated peace—rather than the one his commander-in-chief wanted him to fight.

McClellan did not hide his contempt for the Lincoln Administration, often employing the most intemperate language. On one occasion he wrote his wife that “I have commenced receiving letters from the North urging me to march on Washington & assume the Govt.” He did not limit the expression of such sentiments to private correspondence with his wife. Lincoln and his cabinet were aware of the rumors that McClellan intended to put “his sword across the government’s policy.”

Lincoln knew that he must take action in order to remind the army of his constitutional role. He did this by disciplining Major John Key, aide-de-camp to general-in-chief Henry Halleck and brother of McClellan’s aide, Colonel Thomas Key. Lincoln wrote to Major Key about his response to a query from a brother officer as to “why…the rebel army [was not] bagged immediately after the battle near Sharpsburg [Antietam].” Key had replied, “That is not the game” “The object is that neither army shall get much advantage of the other; that both shall be kept in the field till they are exhausted, when we will make a compromise and save slavery.”

Lincoln dismissed Key from the service, despite pleas for leniency (and the fact that Key’s son had been killed at Perryville), writing in his record of the event that “it is wholly inadmissible for any gentleman holding a military commission from the United States to utter such sentiments as Major Key is within proved to have done.” Just over a month later, Lincoln finally fired McClellan himself.

Historians have often wondered at Lincoln’s “failure” to appoint a Grant or Sherman earlier in the war. But there is no mystery here. The fact is that Grant’s greatness was not apparent in 1862. Neither was Sherman’s. More importantly, there was little difference between McClellan and Grant concerning how to conduct the war. Grant changed his view only after the bloodletting at Shiloh. He realized that the South could only be subdued by hard fighting. McClellan still believed in “soft” war.

One of Lincoln’s great strengths as commander-in-chief was his decisiveness in relieving failed generals. (In this, he differed greatly from the Confederate president.) In 1862, Lincoln relieved not only McClellan, but also John Pope after Second Manassas and Don Carlos Buell as commander of the Army of the Cumberland. In January 1863, he relieved Ambrose Burnside, McClellan’s successor, after the December 1862 disaster at Fredericksburg. Also in 1863, he relieved Joseph Hooker as commander of the Army of the Potomac early in the Gettysburg campaign, and William S. Rosecrans after his Army of the Cumberland was mauled at Chickamauga.

Lincoln never let sentiment or his personal opinion of an officer get in the way of his assessment of the officer’s military potential. He was willing to accept a great deal from his generals if they would give him victory. The best example of this quality is the letter that Lincoln sent to Major General Joseph Hooker, whom he appointed commanding general of the Army of the Potomac in early 1863.

I have placed you at the head of the Army of the Potomac. Of course I have done this upon what appear to me to be sufficient reasons. And yet I think it best for you to know that there are some things in regard to which, I am not quite satisfied with you…. I have heard, in such a way as to believe it, of your recently saying that both the Army and the Government needed a Dictator. Of course it was not for this, but in spite of it, that I have given you the command. Only those generals who gain successes, can set up dictators. What I now ask of you is military success, and I will risk the dictatorship….

In general, Lincoln performed effectively as a military leader. He understood what had to be done and insisted on it. Though the Union may have possessed a material edge over the Confederacy, a strategy was needed to translate this advantage into victory. This Lincoln supplied and saw through to the end.