Lincoln's non pardon

[L Verge]

There is a genealogy page related to the Beall family that has an extensive article entitled "President Lincoln and the Case of John Yates Beall." It tells you everything you need to know about the trial of Beall and the many attempts to get Lincoln to spare his life -- made by some very important people of the time.

The article was written in 1911, by a New Yorker named Isaac Markens. I am only posting here Mr. Markens comments on the validity of Booth shooting Lincoln in revenge for Beall's execution (Roger, this contains the parts that you cited):

"From the execution of Beall and the assassination of Lincoln has sprung a weird and lurid story for years industriously circulated and eagerly devoured - that Booth's deed was inspired by the President's broken promise of a pardon made to Booth. These are in brief the alleged facts: Beall and Booth were bosom friends, were before the war much together -- as Damon and Pythias -- and they had attended the same school. During the war Booth was with Beall on his Lake Erie expedition. When Beall was captured Booth sought Washington McLean, of Ohio, then in Washington, John P. Hale, United States Senator from New Hampshire, and John W. Forney, to aid in Beall's release. Forney was induced to implore the President to exercise clemency. Hale, McLean and Booth, were driven at midnight to the White House, the president was aroused and there was not a dry eye in the room as Booth knelt at the feet of Lincoln, clasped his knees and begged him to spare Beall's life. All present joined in the request. At last Lincoln with tears streaming down his face took Booth by the hands and promised Beall's pardon. The next morning, Seward said when informed by Lincoln what he had done, that the public sentiment in the North demanded that Beall should be hung and he threatened to resign should the President interfere. Seward carried his point and Beall was hanged. The effect on Booth was terrible. He brooded over schemes of vengeance and the assassination followed.

"Such is the substance of this remarkable theory of Booth's motive which for years formed currency in numerous newspapers and periodicals. The Virginia Historical Society regarded the story as of sufficient importance for incorporation in its official publications. Its genesis is uncertain but there is reason for believing that it was conceived in the brain of Mark M. Pomeroy, the notorious editor of "Pomeroy's Democrat," a sensational weekly published shortly after the war. John W. Forney in 1876 publicly branded the story so far as it relates to his knowing or meeting Booth during his lifetime, as an utter fabrication and he incidentally mentions the name of "Mr. Pomeroy" as the author of the story as originally printed not long before. Forney adds that if Lincoln made such a promise to Booth as alleged he would have fulfilled it at all hazards and that Seward would have been the last man in the world to ask him to break his word.

"It is a matter of common knowledge that Booth's designs on Lincoln antedated Beall's operations by quite a remote period. Extensive research fails to disclose the slightest evidence of any acquaintance or intercourse of Beall and Booth prior to or during the war. Finally, the question of Booth's motive in killing Lincoln so far as it involves Beall is disposed of by Booth's own record in his so-called diary of his movements after the assassination wherein is found under the date of April 21 the entry: 'know no private wrong. I struck for my country and that alone.' This diary is in the possession of the War Department."