"U-30" began her first patrol operating from Lorient and her seventh overall on 13 July 1940. During a period of 12 days, she traveled as far south as Portugal and sank the 712-ton British ship "Ellaroy" on the 21st. Three days later, on 24 July, "U-30" returned to Lorient, having experienced a malfunction in one of her engines. It then became clear that the boat was suffering a number of mechanical difficulties and as a result it was decided that she would need to be used sparingly. For her next patrol it was decided that she would leave from Lorient, but would return to Germany.