"Gunnel" was deployed as part of the November 1942 invasion of French North Africa. Operating conditions for the five submarines sent there were not favorable, due to overcrowded waters, poor weather, and mixed-up signals, and the deployment had no accomplishments. Like many other U.S. submarines, "Gunnel" was attacked in error by friendly aircraft. The Hooven-Owens-Rentschler (H.O.R.) diesels (known as "whores") which powered "Gunnel" were troublesome; at one point while returning home, drive gears of all four of the main engines were out of commission, and McCain's crew had to rely on their tiny auxiliary engine for the last . "Gunnel" went into the navy yard for an extensive refit and was replaced on patrol station off North Africa by "Pilly" Lent's .