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).

The ballpark was located at 39°19′26″N 76°36′40″W. Home plate was toward the southwest corner, in the "vee" of the wedge-shaped block. The playing field was small by modern standards. The exact dimensions are not known with precision, but a Baltimore Sun item from May 2, 1935, indicates left field 290 feet (88 m), center field 412 feet (126 m) (it was about 450 before the scoreboard was added), and right field 313 feet (95 m).

This location was directly across the street to the north from Oriole Park (IV), the home of the Baltimore Orioles of the minor International League. 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. The Orioles were solvent again, but could not survive the competition. Dunn pulled the club out of Baltimore after the game of August 22. Although they were still listed as Baltimore in the standings, they staged their September home games in neutral sites such as Wilmington, Delaware. For 1915, Dunn settled the club in Richmond, Virginia, leaving the Terrapins as the sole professional baseball team in Baltimore.

After the Federal League experiment had ended, Dunn created a new Baltimore Orioles club for the International League. Their previous ballpark had been demolished in favor of a Billy Sunday tabernacle. The Orioles arranged to take over the now-vacant property, Terrapin Park, and quickly renamed it the traditional name, Oriole Park (later retroactively labeled Oriole Park V).

Of the new ballparks built by the "Feds", the longest-lasting has been Chicago's Wrigley Field, which was made of steel and concrete. Terrapin Park had been built primarily of wood. That decision would prove to be its undoing, but its eventual demise would boost Baltimore's chances of returning to the major leagues.

Following the demise of the "Feds", the Baltimore professional baseball interests became a primary party in an antitrust legal suit filed against Major League Baseball and involving the Commissioner of Baseball. This resulted in the landmark 1922 U.S. Supreme Court decision, in Federal Baseball Club v. National League, that exempted baseball from antitrust laws.

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