 The O 'Brien class of destroyers was a class of six ships designed by and built for the United States Navy shortly before the United States entered World War I. The O 'Brien class was the third of five classes of destroyers that were known as the " thousand tonners " , because they were the first U.S. destroyers over 1 @,@ 000 long tons ( 1 @,@ <unk> t ) displacement . 
