Mary Todd Lincoln, during her stay at a sanitarium, wrote letters that later were withheld by her only living son, Robert. He supposedly wanted to erase from history the sad details of his mother's mental health and possibly her furious accusations that he had betrayed her. So history records Robert as having burned the letters.

But last summer, historian Jason Emerson, while on a fact-finding mission, found himself staring speechless into a steamer trunk gathering dust in a Maryland attic.

There they were, or at least the next best thing.

Emerson found photographed and handwritten copies of the letters, as well as a 111-page manuscript about Mrs. Lincoln's insanity case, written by the granddaughter of Mary's legal advisers, Myra and James Bradwell.

Emerson also uncovered pages from Mary's 1873 will and copies of letters written the years immediately before and after Mary's recovery at the private Bellevue Place in Batavia. Of the 25 letters Emerson uncovered, 11 were from her so-called "insanity years."

The steamer trunk was in the attic of a home owned by descendents of one of Robert's family attorneys. The copied letters Emerson found appear to be accurate.

The documents contain no eye-popping revelations, the kind that

would require a rewrite of history. Still, Emerson's find adds layers to the mother-son drama that left Mary and Robert estranged until a year before Mary's death in 1882 in Springfield.

"(The letters) show Mary questioning her religious faith, illuminate her continuing mania about money and clothing, and perhaps most interesting, reveal the Bradwells to have been more instrumental than previously known both in securing her release and in causing her resentment of Robert," Emerson writes in the June-July issue of American Heritage magazine.

Some of the letters Emerson discovered were written by Mary when she toured Europe after her release from Bellevue Place. Their contents confirm that her state of mind had improved.

"They are calm, rational and cogent, full of descriptions of her travels and inquiries about friends and events at home," Emerson writes.

His discovery began with a paper trail while working on a biography of Robert Todd Lincoln that Emerson is writing for Southern Illinois University Press.

"He was an amazing man who gets a really bad rap," Emerson said of Robert, adding that he was not the "rapacious bastard" who coldly locked his mother up in an insane asylum.

Emerson is writing another book for SIU Press about the Mary letters.

How he came across copies of the "lost letters" is just as interesting as the letters themselves.

Apparently, the Bradwells' granddaughter, Myra Pritchard, the one who wrote the 111-page manuscript, possessed the original letters, which her mother had kept safe from Robert's fireplace. After Robert died, Pritchard approached Robert's wife, Mary Harlan Lincoln, about her draft. Mary Harlan, with the help of family lawyers who threatened to sue Pritchard, ended up wresting away the manuscript, letters and any copies.

Emerson suspects, however, that Mary Harlan's lawyers kept their own copies of everything and put them in the steamer trunk, which was passed down to their children, whose Maryland home Emerson visited last summer.

Ironically, Pritchard secretly made other copies, but destroyed them after Oliver Barrett, a prominent Chicago lawyer and Lincoln collector, persuaded her the copies were unethically obtained and should be burned. Still, she kept documentation of the letters that helped Emerson verify that the copies he found are based on the originals.

Kim Bauer, curator of the Abraham Lincoln Presidential Library and Museum, also signed off on the documents.

"Clearly, everyone is going to look at this," said Tom Schwartz, Illinois state historian, interim director of the Abraham Lincoln Presidential Library and Museum and a highly regarded Lincoln expert. "I don't see any major revelations, but again, I'm not working on an extensive biography of any of the leading players, either. So much of the story has been pieced together by existing information."

Emerson, who once was a park ranger at the Lincoln Home National Historic Site and lives in Fredericksburg, Va., said he feels this is the kind of thing historians dream about.

"This is a once-in-a-lifetime discovery," he said.

Pete Sherman can be reached at 788-1539 or pete.sherman@sj-r.com.