Editing Isser Harel (section)

=== Intelligence in the Pre-State Era ===
With the outbreak of [[World War II]], Yisrael felt he could not continue his profitable work while his friends enlisted in the [[British Army]] or the [[Palmach]]. In 1942, he approached the [[Haganah]] in Herzliya and volunteered. This was during the period when [[Erwin Rommel]]'s German forces were advancing toward Palestine (a period known as the "200 Days of Dread"). The Haganah decided that priority should be given to the defense of the land and sent Yisrael to a Haganah commander's course. Upon returning from the course, he was assigned to the coastal guard in British uniforms, but his main activity was within the Haganah's intelligence service, the [[Shai (Haganah unit)|Shai]]. Yisrael was reassigned from the coastal guard after he assaulted a corrupt British officer who made [[antisemitic]] remarks. He was placed in the [[Jewish Settlement Police]] (the Notrim) while continuing his role in the Shai.

In 1944, Yisrael was summoned by [[Israel Amir]] (Zabludovsky), the commander of the Shai, who informed him that he was being assigned to serve in the Shai headquarters in [[Tel Aviv]]. This marked the beginning of his long career in commanding positions within the intelligence services of the pre-state Yishuv and later the intelligence community of Israel.

Yisrael began working at the Shai headquarters in Tel Aviv at the end of 1944, serving as the secretary of the "Jewish Department." The department was headed by Yosef Karo, and Yisrael served as his assistant. The department's role was internal security, and it dealt, among other things, with gathering intelligence on underground movements that did not accept the authority of the national institutions, such as the [[Irgun]] and [[Lehi (militant group)|Lehi]], as well as on the activities of [[Communism|communists]]. A few months after starting as the department's secretary, Yisrael was appointed to head the department.

In 1947, Yisrael's name came to the attention of [[David Ben-Gurion]]. He was introduced to Ben-Gurion and reported on the activities of his department. During that meeting, Ben-Gurion decided to rename the "Jewish Department" to the "Internal Department." Yisrael succeeded in his role and became an unofficial spokesman for the Shai. He maintained fair relations with members of other underground movements, who were under his department's surveillance.

At the Shai headquarters, Yisrael earned the nickname "Isser the Small," both due to his short stature and to distinguish him from "Isser the Great," [[Isser Be'eri]] (Birenzweig), who joined the Shai headquarters in 1947 and was tall in stature. Be'eri later became the head of Israeli Military Intelligence, but was dismissed following the Ali Qassem Abed al-Qader affair.

In 1947, Yisrael was appointed the commander of the Tel Aviv District of the Shai, responsible for gathering intelligence from Arab [[Jaffa]]. This was a challenging period for the Shai, following Black Saturday and due to the decline in the number of Arab informants, a result of the national awakening among Jaffa's Arabs leading up to the [[1947–1949 Palestine war|War of Independence]]. Yisrael took steps to recruit new sources and succeeded in doing so. Shortly before the declaration of the State of Israel, Yisrael deployed an Arab agent on a mission to [[Amman]] to assess Jordan's intentions and whether they planned to go to war. The agent reported that the Jordanians intended to join the war, and Yisrael hurried to inform Ben-Gurion.