Abraham Lincoln’s legacy as the Great Emancipator is so indelibly stamped in many Americans’ minds that it’s easy to forget that he led a fascinating life prior to his rise to martyrdom.

“One Life: The Mask of Lincoln,” a new exhibit at the National Portrait Gallery, shows the life that Lincoln led before residing in the White House and his growth from a statesman in Illinois to the 16th president.

The exhibit, which runs through July 2009, includes more than 30 images of the Lincoln dating from 1857 to his assassination in 1865.

The exhibit explores how Lincoln’s persona was influenced by photography, through several portraits of him alone, shots of him with his family and two casts of his face.

“One of the ways he connected to people was through photography,” curator David Ward said. “He had a charisma. One of the ways he did that was by being self-deprecating about his looks.”

There are very few candid photos of the president in the collection and even fewer in which he appears happy. Most show the unusually tall president with an expressionless visage. While Lincoln’s height made him appear strong and in command, his appearance wasn’t always an asset.

“His looks were used against him. He was called Honest Ape” by Southerners during the Civil War, Ward said. One of the photos, taken by Alexander Gardner, shows Lincoln speaking with Union Maj. Gen. George McClellan in a tent near a battlefield in 1862. McClellan is dwarfed by Lincoln’s size.

The centerpiece of the exhibit is a cracked-plate portrait, also taken by Gardner. The crack occurred when the photographer removed the plate — the 19th century version of a negative — from the camera and twisted it slightly. Some call the photo ominous because the crack runs through the top of Lincoln’s head in a path similar to the one taken by the fatal bullet fired by his assassin, John Wilkes Booth. The photo is also one of a kind.

“It is uniquely rare,” Ward said. “That small sort of Mona Lisa smile, it’s tragedy and small satisfaction.”

The historian is hesitant about putting a price tag on the photo, though he is quick to say it is an important piece of history. Because the photo is more than 100 years old, it cannot be shown continuously, lest it be damaged by light. It will hang in the exhibit until Presidents Day, at which time it will be replaced with a facsimile.

“I think it’s one of the great works of art in American history. The fact is that it is of a well-known individual at a very important moment in American history,” Ward said.

One of the photos in the exhibit is especially haunting. It’s a large shot of Lincoln addressing the crowd from the Capitol steps at his second inauguration.

Booth can be seen lurking in the crowd above the president, while his conspirators John Surratt and Lewis Powell are in the foreground.

“It’s a fairly amazing document,” Ward said.

“The Mask of Lincoln” coincides with many other exhibits celebrating the bicentennial of the 16th president’s birth. This presented the challenge of coming up with an informative, original exhibit.

“We realized early on that there was going to be competition,” Ward said “We have this really inclusive and brilliant collection of photography” to select items from.

The exhibit also contains the last-known photo taken of Lincoln.

Photographer Henry F. Warren took advantage of the lax security in the 19th century and took several candid shots of the president’s son, Tad.

On delivering the photos, Warren persuaded Lincoln to begrudgingly sit for a portrait. This photo of the president sitting on the south balcony of the White House would be the last ever taken.

The exhibit is part of the “One Life” series that organizes photos of a noteworthy person in one room for visitors to see. Past exhibits have included “Kate: A Centennial Celebration,” featuring Katherine Hepburn, and “Walt Whitman, a kosmos.”