Starting At Pearl Harbor
On January 28, 1944, the Grayback left Pearl Harbor on her tenth mission. At this point, people were unaware that this would be the final mission she went on. Before she completely disappeared, a message was sent back to base on February 24th, that said that two Japanese freighters, Toshin Maru and Taikei Maru, sunk and two others were damaged.
Asama Maru and Nanpo Maru
On February 25th the submarine sent another message saying that the crew damaged the Japanese liner Asama Maru, and sunk the Nanpo. Within two days these attacks left the Grayback with just two torpedos so she was supposed to sail to Midway Atoll in the North Pacific to restock.