to protect Allied shipping in the area. On 1 December 1943, British and U.S. military representatives at RAF Lajes Field signed a joint agreement outlining the roles and responsibilities for the United States Army Air Forces (USAAF) and United States Navy (USN) at Lajes Field. The agreement established guidelines and limitations for the ferrying of aircraft and the transport aircraft to Europe via Lajes Field. In return, the US agreed to assist the British in improving and extending existing facilities at Lajes. Air Transport Command transport planes began landing at Lajes Field immediately after the agreement was signed. By the end of June 1944, more than 1,900 American airplanes had passed through this Azorean base. Using Lajes Field, the flying time relative to the usual transatlantic route between Brazil and West Africa was nearly cut in half from 70 to 40 hours. Lajes Field was one of the two stopover and refueling bases for the first transatlantic crossing of non-rigid airships (blimps) in 1944. The USN sent six Goodyear-built K-ships from Naval Air Station South Weymouth in Massachusetts to their first stopover base at Naval Station Argentia, Newfoundland and then on to Lajes Field in the Azores before flying to their final destination at Port Lyautey (Kenitra), French Morocco. From their base with Fleet Air Wing 15 at Port Lyautey, the blimps of USN Blimp Squadron 14 (ZP-14 or Blimpron 14) conducted night-time anti-submarine warfare (ASW) to search for German U-boats around the Strait of Gibraltar using magnetic anomaly detection (MAD). In 1945, two ZP-14 replacement blimps were sent from Weeksville, North Carolina to the Bermudas and Lajes before going on to Craw Field (Kenitra Air Base) at Port Lyautey. Post-War The United States and the United Kingdom transferred control of Lajes back to Portugal in 1946. The Portuguese redesignated Lajes as Air Base No. 4 and assigned it to the air branch of the Portuguese Army. However, talks between the U.S. and Portugal began about extending the American stay in the Azores. A temporary agreement was reached between the U.S. and Portuguese governments giving the U.S. military rights to Lajes Field for an additional 18 months: the relationship between the Portuguese and American governments continues to this day, where the U.S. military resides under a tenancy status, and the Portuguese government retaining rights of ownership to the land and infrastructure. Lajes Field remains Portuguese Air Base 4 under the