 Daunted by the strong British forces at the straits, Heinicke did not attempt to force them and was transferred to the merchant raider on his return to Germany.Harald Grosse replaced Heinicke for "U-53"s third and final war patrol, which began on 2 February 1940.Grosse sank six ships for , including the Spanish neutral "Banderas", whose sinking strained relations between Germany and Spain.