Exquisite broadside advertising a very early baseball game between the New York Mutuals and Yale played in the 1870s. The poster lists the Mutuals as the "Champions of the United States." The team was formed in 1857 and won the National Amateur Association pennant twice - in 1868 and 1870 - before joining the National Association and later the National League for one year. Interestingly, the Mutuals did not fulfill their playing obligations in the National League in 1876, and the following year the team dissolved. The poster has been framed to 23x28" and reads, "Base Ball! Opening Game!" at the top. The game was played at historic Hamilton Park in New Haven. There is minor paper loss to the edges with some minor creasing, otherwise it is VG.