After World War II, the situation for Jews in Iraq deteriorated sharply. Prominent community members like Laura Khozoee were arrested. Shafiq Adas, a successful Jewish businessman, was publicly hanged. These were not abstract threats. Iraqi Jews began to leave. Some went to Israel. Others chose Iran, a country with its own ancient Jewish community and a border that could be crossed with the help of Kurdish Jews who knew the routes. Many refugees arrived at Khorramshahr, on the Persian Gulf, where a prominent local Jew named Harun Abdolnabi helped them obtain legal documents and passage to Tehran. Between 1946 and 1951, a steady stream of Iraqi Jews resettled in the Iranian capital.

Batson carved out 865 square meters of his purchased land for the synagogue, building it with the help of Saleh and Davood Mashi, Heskel Haim, and other community members. The building was designed in the Pahlavi architectural style and fitted with the most advanced cooling system available at the time. But the synagogue's most precious contents were carried across borders in the arms of refugees: Torah scrolls brought from Iraq, and a Babylonian Talmud in Aramaic script, dedicated to the congregation. These objects connected the Ettefagh community not merely to Iraq but to the deep roots of Jewish life in Mesopotamia, a tradition stretching back to the Babylonian exile.

The Ettefagh complex included a private high school known for its strong English-language curriculum. In the 1970s, the Ettefagh School attracted students from across Iran's religious minorities: Christians, Baha'is, and Zoroastrians studied alongside Jewish students. The school was a rare space where Iran's diverse non-Muslim communities shared a daily life centered on education rather than religious distinction. After the 1979 Islamic Revolution, the school was taken over by the state and converted into a girls-only institution. The cross-community character that had defined it vanished with the change of regime.

The 1979 revolution scattered the Iraqi Jewish community of Tehran for a second time. Many emigrated again, some to Israel, others to the United States and Europe. Today only a few families, mainly Iranian Jews rather than the Iraqi community that founded it, still use the Ettefagh Synagogue. A fundraising campaign organized by the Babylonian Jewish Center of New York has helped maintain the building, keeping its walls and Torah scrolls intact. The synagogue endures as a monument to a community that named itself "unity" and was twice pulled apart -- first from Baghdad, then from Tehran.