The Terrapins, as the Baltimore Federal League club was called (a nickname associated with the University of Maryland since 1933), built their ballpark, Terrapin Park, on a wedge-shaped block bounded by 29th Street, York Road (later Greenmount Avenue), 30th Street, and the angling small alley-like Vineyard Lane (originally Gilmore Lane).
This was competition at its most direct, and the established Orioles suffered a drop in attendance so severe that owner Jack Dunn was compelled to sell the contracts of some of his best players, most notably the young left-hand pitching sensation Babe Ruth, who was sent to the Boston Red Sox, as was right-hand pitcher Ernie Shore.
On April 18, 1919, the Red Sox came through town on their way north from spring training, and played an exhibition game at Oriole Park.
That year also saw a lot of excitement on the field, as Joe Hauser of the Orioles began hitting home runs at a record clip, eventually reaching 63, which surpassed Ruth's season high of 60 in 1927.
But on the night of July 3, 1944, a fire of uncertain origin (speculated to have been a discarded cigarette) consumed the old ballpark and every object the team had on-site, including uniforms and trophies.
Literally rising from the ashes, the Orioles went on to win the International League championship, and then the Junior World Series over Louisville of the American Association.
The large post-season crowds that fall of 1944 at Municipal Stadium, which would not have been possible at the old wooden Oriole Park, caught the attention of the major leagues, and Baltimore soon became a viable option for struggling teams who were considering moving to other cities.