ALG meaning in Governmental ?

Advanced Landing Grounds (ALGs) were temporary advance airfields constructed by the Allies during World War II during the liberation of Europe. They were built in the UK prior to the invasion and thereafter in northwest Europe from 6 June 1944 to V-E Day, 7 May 1945.

Unlike the permanent airfields built in the United Kingdom and designed for the strategic bombardment of Germany, the tactical combat airfields on the continent were temporary, often improvised airfields to be used by the tactical air forces to support the advancing ground armies engaged on the battlefield. Once the front line moved out of range for the aircraft, the groups and squadrons moved up to newly built ALGs closer to the ground forces and left the ones in the rear for other support uses, or simply abandoned them.