The Morrissana Union Base Ball Club of New York, claiming the championship of the United States, have resolved at last to come westward. It took many invitations to win their approval, and more to precipitate their departure. They left on the Albany boat, Sunday, July 19, and anticipate a return on the 28th of August...The following is the official list of the clubs to be played, with the dates:
...Aug. 14. - Union, of St. Louis, Mo.
Aug. 15. - Empire, of St. Louis, Mo....
Let the Unions and the Empires of our city gird on their armor for the tourney a l'outrance. There must be hot work, and swift work, and cool work, too, if either hope to win. Victory is possible, and such a victory would lift the winning club up into the seventh heaven of base ball renown.
-Missouri Republican, July 22, 1868
The Unions of Morrisania were indeed officially recognized as the national champions but it was, like a lot of the official championships of this era, a disputed championship. But make no mistake, they were a darn good club and I think it's kind of neat that the defending national champion came to St. Louis in 1868 (although, I'm sure that both the Athletics and Atlantics would argue that the defending national champions had already visited St. Louis).