The four years and almost two months that Abraham Lincoln served as president were wrenching. We know something of what the nation endured in the blood and ashes of the Civil War. More than 1.1 million Americans—almost three percent of the population— were killed or wounded in a conflict that tore families apart even as the country itself split open.

We know much less of what (and how) Lincoln himself endured from his place at the center of this terrible, perfect storm. Physically, intellectually, emotionally, and spiritually it pushed the man who was our sixteenth president close to the breaking point. Over and over again. In physical terms, the war robbed Lincoln of his appetite. Never a voracious eater, he grew less and less interested in food as the cares of his office wore into him. His weight dropped: almost 30 pounds—to 150—on his six foot-four-inch frame. His sleep suffered. Countless nights, he paced the main hallway of the second floor of the White House. At times, lost in thought, at others, singing bawdy Scottish ballads in an effort to soothe, distract, himself back to sleep.

He struggled intellectually as well, trying to make sense—for himself and the country—of a conflict that seemingly would never end and of the unprecedented carnage that sustained it. Trying to understand the ultimate meaning and worth of the path he was taking Americans on, at the same time as he considered the significance, tradeoffs, and timing of specific actions. The war would not let him go emotionally either. A sensitive, kind-hearted man, Lincoln took in much of the suffering around him while he grappled with the responsibility he felt for such loss. In early 1862, death came right up the stairs to the family living quarters as Lincoln and his wife Mary watched their son Willie succumb to typhoid fever. “My boy—he is actually gone!” Lincoln sobbed to his secretary that dark February day. And through it all, he had to find the strength and will within himself to continue to lead a nation increasingly weary of war—so weary that by 1864, many Northerners wanted a brokered peace with the Confederacy.

Lincoln’s spiritual experience was hardly less difficult. In his now-famous speeches, we can see him contending with the possibility of larger forces at work in this awful war. “The Almighty has His own purposes,” he declared in his second inaugural address, attributing the magnitude and duration of the conflict to a higher power. In a private musing, most likely written in the fall of 1862 after the bloodbath that was the battle of Antietam, he speculated that God “could have either saved or destroyed the Union without a human contest. Yet the contest began. And, having begun He could give the final victory to either side any day. Yet the contest proceeds.”

In all these respects, the Civil War cost Lincoln dearly. (Think of the stark contrast in the photographs taken of him at the beginning and then again, at end of the war). What sustained him? Why was he willing to wager so much, collectively and personally, to accomplish his mission of saving the Union? What was it about the Union, which he called, “the last best hope of earth,” that made it worth paying so high a price?

Late in the war, he took up these issues. Speaking before the 166th Ohio Regiment, he compared his own journey to that of countless other Americans: “I happen to temporarily occupy this big White House. I am a living witness that any of your children may look to come here as my father’s child has. It is in order that each of you may have through this free government which we have enjoyed, an open field and a fair chance for your industry, enterprise and intelligence; that you may all have equal privileges in the race of life, with all its desirable human aspirations. It is for this the struggle should be maintained.”

It was maintained. And through that struggle, the Union was saved. The ultimate meaning of that preservation, including Lincoln’s leadership and what such leadership cost him, is manifest now: as the child of the father of Barack Hussein Obama becomes our 44th president.