that the Arab leaders spread rumors of atrocities that did not actually occur, which only added to the Palestinian Arabs' fears. According to Avraham Sela, the Palestinian exodus began with news of the Zionists' military victories in April–May 1948: [T]he offensive had a strong psychological effect on Palestinian-Arab villagers, whose tendency to leave under Jewish military pressure became a mass exodus.... [T]he exodus was a spontaneous movement, caused by an awareness of the Arab weakness and fear of annihilation typical in civil wars. Moreover, an early visible departure of nearly all the leadership was clearly understood as a signal, if not as an outright command. In his conclusions concerning the second wave of the flight, Morris also cites the atrocity factor as one of the causes. What happened or allegedly happened and in a more general way the massacre of Deir Yassin and its exaggerated description broadcast on Arab radio stations undermined Arabs' morale. Yoav Gelber also considers that the "Haganah, IZL and LHI's retaliations terrified the Arabs and hastened the flight". One Arab source at the time stated, "Had the Arab leaders not disseminated horrific stories about Deir Yasin the residents of the Arab areas in Palestine would not have run away from their homes." Childers, while dismissing the fact that Arab leaders instigated the flight on radio broadcasts, points out that Zionist radio broadcasts were designed to demoralize the Arab audience. The author cites the fact that rumours were spread by the Israeli forces that they possessed the atomic bomb. Similarly, Khalidi points to what he describes as the Zionist "psychological offensive" which was highlighted by, though not limited to, radio messages warning the Arabs of diseases, the ineffectiveness of armed resistance and the incompetence of their leaders. Psychological warfare The Yishuv used psychological warfare that initiated, accelerated and increased the Palestinian exodus. In many instances the declared aim was to demoralise the Palestinians or to accelerate their surrender. In many instances however the result was the flight of Palestinians. One method was Zionist radio broadcasts. On March 17, four days before the Jewish offensive, the Irgun made an Arabic-language broadcast, warning urban Arabs that "typhus, cholera and similar diseases would break out heavily among them in April and May". Similarly, Khalidi points to what he describes as the Zionist "psychological offensive" which was highlighted by, though not limited to, radio messages warning the Arabs of diseases, the