Established on August 14, 1855, Atlantic became a founding member of the National Association of Base Ball Players, the amateur sport's first governing body, in 1857.

Atlantic held the championship again through the 1861 season, which was shortened due to the American Civil War, before finally surrendering it to archrival Eckford of Brooklyn in 1862.

Atlantic went undefeated in 1865 with an 18–0 record, sweeping series against chief rivals Mutual of New York and Athletic of Philadelphia.

Great players of this era included Joe Start, Dickey Pearce, Charlie Smith, Fred Crane, and Tom Pratt.

An estimated crowd of 15,000 paid 50 cents a piece to see Atlantic win 8–7 in extra innings in one of the most significant games in baseball history.

A daguerreotype of the Atlantics presenting an official team jersey to the President bearing the number “65” is on display at the National Baseball Hall of Fame in Cooperstown, New York.

As a result, their best players, including George Zettlein, Bob Ferguson, Joe Start and Lip Pike, jumped to other clubs.

When Atlantic did join the professional circuit in 1872, it was unable to reestablish itself as a leading club, suffering losing records in each of its four seasons in the league.