About Ernest Thayer
Ernest Lawrence Thayer was an American writer and poet who wrote the poem "Casey", which is "the single most famous baseball poem ever written" according to the Baseball Almanac, and "the nation’s best-known piece of comic verse—a ballad that began a native legend as colorful and permanent as that of Johnny Appleseed or Paul Bunyan". Team Sport's First Media Sensation and Baseball's Original Casey at the Bat, reprints a 1905 Thayer letter to a Baltimore scribe who was asking about the poem's roots. The first public performance of the poem was on August 14, 1888, by actor De Wolf Hopper, on Thayer's 25th birthday.
Biography source: Wikipedia. The profile adds birthday-specific historical context from the Celebs Birthday Today editorial database.