Italian and German submarines operated in the Mediterranean on the Axis side while French and British submarines operated on the side of the Allies. The German Navy sent 62 U-boats to the Mediterranean; all were lost in combat or scuttled. German subs first had to pass through the highly defended Straits of Gibraltar, where nine were sunk, and a similar number damaged so severely they had to limp back to base. The Mediterranean is calmer than the Atlantic, which made escape for U-boats more difficult and was ringed with Allied air bases. Similar ASW methods were used as in the Atlantic but an additional menace was the use by Italians of midget submarines.