Everything changed on the night of August 18.

That evening, Rasher picked up radar contact on a large formation. It was no ordinary convoy. This was one of the most important Japanese supply efforts of the war, bound for the Philippines with troops and materiel. The convoy stretched in multiple columns, bristling with escorts, and covered by aircraft. To the American submarines waiting in the area, it was the opportunity of a lifetime. To the Japanese, it was a last chance to reinforce a crumbling position.