Balabac Strait
"Dace" cleared Brisbane on 1 September on her fifth and most successful war patrol. She topped up her fuel tanks at Darwin, Australia on 10 September, and sailed for the exacting task of sweeping mines in Palawan Passage and Balabac Strait. From 27 September – 3 October, she put in at Mios Woendi to repair her gyrocompass, returning to her patrol area on 10 October. Four days later, she attacked a convoy of seven ships, sinking two and heavily damaging a third.