 After the United States entered the war in April 1917 , all six class members were sent overseas to Queenstown , Ireland , for convoy escort and anti @-@ submarine duties . McDougal was in the first group of six American destroyers that arrived at Queenstown on 4 May ; Ericsson and Winslow followed in the second group , which arrived thirteen days later , and Cushing , Nicholson , and O 'Brien in the third group , a week after that . Several of the ships had encounters with U @-@ boats during the war : Nicholson , working with Fanning in November 1917 , helped to sink U @-@ 58 , which was the first U @-@ boat sunk by the U.S. Navy ; earlier , in June , O 'Brien had depth @-@ charged U @-@ 16 and was thought by the British Admiralty to have seriously damaged the U @-@ boat , but post @-@ war analysis of records showed that U @-@ 16 survived the attack and returned safely to port . 
