 Meanwhile , salvage efforts on Yorktown were encouraging , and she was taken in tow by USS Vireo . In the late afternoon of 6 June , the Japanese submarine I @-@ 168 , which had managed to slip through the cordon of destroyers ( possibly due to the large amount of debris in the water ) , fired a salvo of torpedoes , two of which struck Yorktown . There were few casualties aboard , since most of the crew had already been evacuated , but a third torpedo from this salvo struck the destroyer USS Hammann , which had been providing auxiliary power to Yorktown . Hammann broke in two and sank with the loss of 80 lives , mostly due to her own depth charges exploding . With further salvage efforts deemed hopeless , the remaining repair crews were evacuated from Yorktown , which sank just after 05 : 00 on 7 June . 
