Forerunners of the Israeli Air Force were the Palestine Flying Service established by the Irgun in 1937, and Sherut Avir, the air wing of the Haganah. The Israeli Air Force formed on May 28, 1948, shortly after Israel declared statehood and found itself under attack. The force consisted of a hodge-podge of commandeered or donated civilian aircraft converted to military use. A variety of obsolete and surplus ex-World War II combat-aircraft were quickly sourced by various means to supplement this fleet. The backbone of the IAF consisted of 25 Avia S-199s (purchased from Czechoslovakia, essentially Czechoslovak-built Messerschmitt Bf 109s), and 60 Supermarine Spitfire LF Mk IXEs, the first of which, "Israel 1", was locally assembled from British abandoned spare parts and a salvaged engine from an Egyptian Air Force Spitfire with most of the rest purchased from Czechoslovakia.