In May 1940, 101 ships were sunk—but only nine in the Atlantic—followed by 140 in June; 53 of them in the Atlantic for a total of that month. The first six months in 1940 cost Dönitz 15 U-boats. Until mid-1940 there remained a chronic problem with the reliability of the G7e torpedo. As the battles of Norway and Western Europe raged, the "Luftwaffe" sank more ships than the U-boats. In May 1940, German aircraft sank 48 ships (), three times that of German submarines. The Allied evacuations from western Europe and Scandinavia in June 1940 attracted Allied warships in large numbers, leaving many of the Atlantic convoys travelling through the Western Approaches unprotected. From June 1940, the German submarines began to exact a heavy toll. In the same month, the "Luftwaffe" sank just 22 ships () in a reversal of the previous months.