In 1947, the 'Mossad le-aliyah bet' (a secret branch of the Hagana devoted to bringing in illegal immigrants, which later evolved into the 'Mossad') managed to make contact with two American pilots who were willing to fly illegal immigrants to Jewish Palestine, in exchange for a hefty fee. The two would be using a Curtiss Commando transport which they owned. On August 20th 1947, the pilots flew Aliyah-bet agent Shlomo Hillel to Baghdad. Hillel carried out some quick organizational work, and at night a group of 50 youths from the 'Hehalutz' movement boarded the plane.
It was dawn when the plane landed in an improvised strip that had been prepared a few days earlier by Palmah members in the Yavne'el valley. The landing strip was 600 or 700 meters long, and was marked with the aid of bundles of hay that had been set alight. Five minutes after the plane had landed, the new olim (immigrants to Israel) had been taken off the plane and scattered among the neighboring Jewish settlements. The plane took off hurriedly to Rome.
Following the operation's success, 50 additional olim were brought in in September, this time from an abandoned field near Naples, Italy. The plan called for the Curtiss to continue from Yavne'el on to Baghdad for a repeat version of the first operation, but the pilots got cold feet and refused to go. However, on September 20th 1947 they surprised everyone by landing in Baghdad with their plane, ready for another flight to Palestine. A group of olim was hastily called together, but initially the Aliyah-bet officials refused to authorize the takeoff, because of the night curfew imposed on Palestine by the British. By 23:00, however, night curfew notwithstanding, the landing strip at Yavne'el had been readied and the plane took off.
A few hours later, the plane landed and the settlements in the Yavne'el area again took in 50 immigrants. This was the last flight in Operation Michaelberg - so named after the two pilots-for-hire involved: the captain, Leo Vessenberg, and the copilot, whose name was Mike.