Avia S-199 - Israeli Users, Part one

Back in 1948, when Israel was fighting for his independence, their agents negotiated the purchase from the Czechoslovak government in a clear defiance of the arms embargo imposed to Israel at the time.

They negotiated the bought of twenty-five aircraft but only two of them were eventually delivered to the newly created Israeli Air Force. Each of the airplanes costed 190000$ of the time and the first airplanes arrived in Israel on 20th May 1948, just six days after the declaration of independence and five days after hostilites with Egypt began.

It could be safe to say that they were the very first fighters to equip Israel's Air Force and in fact, they formed their first squadron, the 101 Tajeset. After being assembled, they were sent into combat for the first time on 29th May 1948 when they attacked an Egyptian army convoy between Isdud and Ad Halom bridge, located at the south of Tel-Aviv. A few days later, on June 3rd, this type of aircraft scored the IAF first victory when an S-199 piloted by Modi Alon shot down two Egyptian Douglas C-47 Dakota that had just bombed Tel-Aviv.

Sources: 
1. https://en.wikipedia.org/wiki/Avia_S-199
2. Salamander Books - The Complete Book of Fighters