During the next five years, the Radiation Laboratory made stunning contributions to the development of microwave radar technology in support of the war effort. Inventions included airborne bombing radars, shipboard search radars, harbor and coastal defense radars, gun-laying radars, ground-controlled approach radars for aircraft blind landing, interrogate-friend-or-foe beacon systems, and the long-range navigation (LORAN) system. Some of the most critical contributions of the Radiation Laboratory were the microwave early-warning (MEW) radars, which effectively nullified the V-1 threat to London, and air-to-surface vessel (ASV) radars, which turned the tide on the U-boat threat to Allied shipping. In November 1942, U-boats claimed 117 Allied ships. Less than a year later, in the two-month period of September to October 1943, only 9 Allied ships were sunk, while a total of 25 U-boats were destroyed by aircraft equipped with ASV radars (Buderi, pp. 155–169). "