“Base Ball. Knickerbocker vs. Eagle Club (Headline). A grand match of this national game was played yesterday, at the Elysian Fields, Hoboken, between the above clubs, which resulted in favor of the Knickerbocker by thirteen runs.” New York Herald, June 6, 1855, p1
Previous earliest use (Dickson Baseball Dictionary, 3rd edition, 2009):
1ST USE. 1855. “[Base ball clubs are encouraged to participate in] a similar interchange of civilities…productive of the best results to all interested in this truly National game” (New-York Daily Tribune, Aug. 7; Tom Shieber).