 The American convoy carrying the first units of the American Expeditionary Force was broken into four groups ; El Occidente was in the fourth group with Montanan , Dakotan , and Edward Luckenbach , and escorts consisting of cruiser St. Louis , U.S. Navy transport Hancock , and destroyers Shaw , Ammen , and Flusser . El Occidente departed with her group on the morning of 17 June for Brest , France , steaming at an 11 @-@ knot ( 20 km / h ) pace . A thwarted submarine attack on the first convoy group , and reports of heavy submarine activity off of Brest resulted in a change in the convoy 's destination to Saint @-@ Nazaire . 
