Mark Twain's seventh contribution to The Californian, "The Killing of Julius Caesar 'Localized,'" ran on November 12, 1864, and he liked the story well enough to reprint it three years later in his first book, The Celebrated Jumping Frog of Calaveras County, and Other Sketches.
Twain's parody cuts two ways: knocking Shakespeare down to size and at the same time imitating the kind of sensationalist newspaper coverage of murders so popular at the time (and to which he himself had contributed when writing for The Morning Call). Twain had been toying with Shakespeare parodies from the outset of his writing career.
