Brilliant, Roger, this is correct. He and Orpheus C. Kerr (both noms de plume) were said having been Abraham Lincoln's favorite humorists.
At the meeting of Lincoln's first reading of the EP to his cabinet, Lincoln insisted in first reading a passage by Ward to the "appointed audience" - not all of which could share (t)his sense of humor. Edwin Stanton said that Abraham Lincoln "was reading a book of some kind, which seemed to amuse him. It was a little book. He finally turned to us and said: 'Gentlemen, did you ever read anything from Artemus Ward? Let me read you a chapter that is very funny.' Not a member of the Cabinet smiled; as for myself, I was angry, and looked to see what the President meant. It seemed to me like buffoonery. He, however, concluded to read us a chapter from Artemus Ward, which he did with great deliberation, and, having finished, laughed heartily, without a member of the Cabinet joining in the laughter. 'Well,' he said, 'let's have another chapter,' and he read another chapter, to our great astonishment. I was considering whether I should rise and leave the meeting abruptly, when he threw his book down, heaved a sigh, and said: 'Gentlemen, why don't you laugh? With the fearful strain that is upon me night and day, if I did not laugh I should die, and you need this medicine as much as I do.'"