The "thousand tonners" were the 26 United States Navy destroyers of five classes—Cassin, Aylwin, O'Brien, Tucker, and Sampson—so named because they were the first U.S. Navy destroyers to have displacements greater than 1,000 long tons.
The Cassin class, the first of the thousand tonners, displaced about a third more than the preceding Paulding class.
The introduction of the thousand tonners led to the Pauldings and other older, smaller displacement destroyers of previous classes to be dismissively called "flivvers", a nickname also commonly applied to the Ford Model T.
The O'Brien class was the third of the five classes of "thousand tonners".
The earlier Cassin- (DD-43 to DD-46) and Aylwin-class (DD-47 to DD-50) ships were about the same length as the O'Brien ships and all had median displacements in the range of 1,020–1,050 long tons (1,040–1,070 t); the later Tucker- (DD-57 to DD-62) and Sampson-class (DD-63 to DD-68) ships were about 10 feet (3.0 m) longer and had median displacements of 1,090–1,100 long tons (1,110–1,120 t).
All five classes were armed with four 4-inch (102 mm) guns, but the torpedo size and complement varied.
All were equipped with four twin torpedo tubes loaded with eight torpedoes except for the Sampsons (which had four triple tubes carrying twelve torpedoes), but the Cassin  and Aylwin classes were armed with 18-inch (457 mm) torpedoes.
The O'Brien ships were the first armed with the new 21-inch (533 mm) Mark 8 torpedoes; the Tucker and Sampson ships also used the 21-inch torpedoes.
The Sampsons were the only group originally equipped with anti-aircraft guns, a pair of 1-pounder (0.45 kg) guns with a caliber of 37 mm (1.46 in).
The "thousand tonners" were the 26 United States Navy destroyers of five classes—Cassin, Aylwin, O'Brien, Tucker, and Sampson—so named because they were the first U.S. Navy destroyers to have displacements greater than 1,000 long tons. The Cassin class, the first of the thousand tonners, displaced about a third more than the preceding Paulding class. The introduction of the thousand tonners led to the Pauldings and other older, smaller displacement destroyers of previous classes to be dismissively called "flivvers", a nickname also commonly applied to the Ford Model T.
The O'Brien class was the third of the five classes of "thousand tonners". The earlier Cassin- (DD-43 to DD-46) and Aylwin-class (DD-47 to DD-50) ships were about the same length as the O'Brien ships and all had median displacements in the range of 1,020–1,050 long tons (1,040–1,070 t); the later Tucker- (DD-57 to DD-62) and Sampson-class (DD-63 to DD-68) ships were about 10 feet (3.0 m) longer and had median displacements of 1,090–1,100 long tons (1,110–1,120 t). All five classes were armed with four 4-inch (102 mm) guns, but the torpedo size and complement varied. All were equipped with four twin torpedo tubes loaded with eight torpedoes except for the Sampsons (which had four triple tubes carrying twelve torpedoes), but the Cassin  and Aylwin classes were armed with 18-inch (457 mm) torpedoes. The O'Brien ships were the first armed with the new 21-inch (533 mm) Mark 8 torpedoes; the Tucker and Sampson ships also used the 21-inch torpedoes. The Sampsons were the only group originally equipped with anti-aircraft guns, a pair of 1-pounder (0.45 kg) guns with a caliber of 37 mm (1.46 in).
O'Brien-class destroyer