Base Ball. – The Rocky Mountain Base Ball Club has made a fair start. The weather in the beginning of the week was very stormy, but the boys were of the right sort, ardent as a burning glass and tough as hickory; so, despite of wind or weather, they declared they would have their knock at the ball. The subjoined score was made under every disadvantage of weather. The wind blew a hurricane, and the players were compelled to leave their chosen ground and to take refuge in a hollow, not so well fitted for the sport, near the new burying-ground; and even then the wind was most annoying. The game was, however, well played, and, as our record will hereafter show, there is no lack of active young men in this community. Ben Ezekiel was umpire and Ben S. Word, scorer. The game will be played at least once a week, and we believe will attract much notice from the community, as well as being a great benefit to the members and much fun for the players.
-The Montana Post [Virginia City, Montana Territory], June 2, 1866
I believe that this club is rather unique for the American West of this period because it was a club made up of the young men of Virginia City rather than one made up of soldiers who had been stationed in the area. This reference also predates the earliest reference to Montana baseball at Protoball by two years.