The PBY Catalina was also employed by the RAAF as a long range bomber and mine-layer. The Catalinas excelled in the latter role, for while their low speed made them vulnerable to fighters, it also allowed them to accurately lay mines while flying. Four squadrons laid mines from April 1943 to July 1945 in the southwest Pacific. These operations blockaded ports and shipping routes. They also forced Japanese shipping into waters where American submarines were present. RAAF mining missions were often conducted at night to minimize the risk of interception and were hazardous, with some aircraft flying as low as above the surface to perform an accurate drop. These operations could last over 20 hours. In 1944 RAAF Catalinas flew missions to the Philippines and laid naval mines in Manila Bay to interdict the Japanese navy and prevent their intervention in the Battle of Mindoro. The motto of the crews who conducted these operations was "The First and the Furthest."