The initial agreement for the integration of the Irgun into the IDF did not include Jerusalem, where a small remnant of the Irgun called the "Jerusalem Battalion", numbering around 400 fighters, and Lehi, continued to operate independently of the government. Following the assassination of UN Envoy for Peace Folke Bernadotte by Lehi in September 1948, the Israeli government determined to immediately dismantle the underground organizations. An ultimatum was issued to the Irgun to liquidate as an independent organization and integrate into the IDF or be destroyed, and Israeli troops surrounded the Irgun camp in the Katamon Quarter of Jerusalem. The Irgun accepted the ultimatum on September 22, 1948, and shortly afterward the remaining Irgun fighters in Jerusalem began enlisting in the IDF and turning over their arms. At Begin's orders, the Irgun in the diaspora formally disbanded on January 12, 1949, with the Irgun's former Paris headquarters becoming the European bureau of the Herut movement.