During Israel's War of Independence, the U.S. Government had emposed a weapons embargo on all warring sides in the Middle East. Still, Israeli aquisition agents managed to purchase 4 surplus U.S. Air Force B-17 Flying Fortresses, veterans of World War II, and these slipped from watchful American eyes to Ezion, the Israeli name for an air base in Czechoslovakia which aided Israel with weapon sales and shipment. One Fortress was seized on its way in Portugal and so only 3 arrived in Ezion. Having been neglected for a long time, they were devoid of guns and navigational gear, with turret holes gaping open or sealed with wood or plaster. The Fortresses landed in Ezion on June 17th, 1948 and received the most rudimentry of treatments before leaving for Israel on July 15th. On the way home one B-17 bombed Cairo, surprising the Egyptians who thought they were immune to
such attacks and so left their capital undefended (Egyptian attacks on Israeli civilian targets stopped after this). The other two bombed Egyptian forces in Gaza and Rafiah. For the rest of the war the B-17 were stationed in Ramat David AFB and participated in operations on all fronts, even against the Egyptian navy.The Fortresses were also the founders of the IAF's 69th squadron, the "Patishim" (Hammers) which
exists to this day.
Although one of the most important bombers of WWII, the young IAF had no need for such a large, long-range bomber. During the 1956 Suez Crisis, the 3 Fortresses went on a small number of sorties, and were finally scrapped in 1958.
Sources: IAF Inventory