第38任務部隊
On 3 August, "Porterfield" was detached from the carrier group to join the Fast Carrier Task Force (then 5th Fleet's TF 58). She rendezvoused with Task Group 58.4 (TG 58.4) east of Guam 6 August and operated with that group during the rest of the Guam campaign, returning to Eniwetok 10 August.