Mendel Rosentul, the head of the pantry and dining room at the trade and production office (TPO) of the Proskurov NKVD, had a high reputation among the Chekists. As a hardworking young man who had previously been a junior commander in the Red Army, he worked for several years at an organization where NKVD employees and their families shopped and dined. And then, colleagues made a surprising discovery: Benzion Ginsburg, an experienced and courageous underground worker, was hiding behind the mask of Mendel Rosenblum, whom they all knew.

On January 3, 1937, in Proskur, Benzion Ginburg was arrested and became one of the last leaders of the Zionist underground right in the Soviet Union to remain at large.Under various pseudonyms, Benzion Ginzburg (or Boris in the Russian way) has lived since 1928. At one point he used fake documents in the name of Chaim Sorokin. Then he was known as Lev Bir. In January 1931, he became Mendel Ikhlelevich Rosenthal. In Zionist circles, he was also known by the party nickname Joseph.

Ginzburg was born in 1909 in Lyantskoru, Kamenets district. His father Gershko was a small trader. He struggled to provide his son with a proper education during the First World War. Nevertheless, Ginsburg grew up smart and interested in Jewish history and culture.Even as a teenager, Benzion organized a circle of Hebrew language lovers in his native Lyantskorun. However, he did not stop at pure culture: fierce disputes between youth leaders took place around the guy. Some called on the Lyantskoru children to join the Komsomol, while others urged them to prepare for the construction of their own country – Eretz Israel.

The latter idea seemed the most logical to Benzion, since the Poles and Czechs already had their own states, but the representatives of the oldest people did not have their own state. Benzion Ginsburg decided that he and his friends would eventually leave for Palestine to build a state for Jews.In order to properly prepare future builders of Eretz Israel, Ginzburg, in the summer of 1924, initiated the creation of a Zionist youth organization called "Hashomer Hatzair" in Lutsk. It was a right-wing or national labor branch of Jewish Scouting, focused on an alliance with the World Zionist Organization and political neutrality in cultural and educational work. Borrowing the scout structure from socialist colleagues, right-wing Shomers not only engaged in national and sports education for Jewish youth, but also actively collected signatures to legalize Hebrew and Jewish culture in the USSR. As a prominent leader of the Lianokorun cell, Benzion Ginzberg was appointed head of the Zionist-created Communications Bureau by a resolution of the Podolsky district headquarters of the movement in May 1928. He was supposed to carry out communication between the Hashomer Hatzair cells in Podolya and was located in Dunaivtsi.

However, caught up in the web of Chekists' agents, the shomers could not hide their location for long. In July 1930, an OGPU agent came to the workshop where Benzion worked with an arrest warrant. Benzion was not there, but soon after approaching the workshop he noticed a strange man of a specific appearance. Quickly climbing onto the roof of a nearby house, Benzion escaped only after the security agent had left.The head of the "Communications Bureau" had to leave Dunayevtsy immediately. Under the guise of a worker, Chaim Sorokin, a Zionist, left for Kyiv.

At that time, a large number of members of Hashomer Hatzair, who had fled from towns, were concentrated in Kyiv. These people, whom activists jokingly called refugees, were led by prominent Zionists such as Abraham Halperin, who arrived from Starokonstantinov. Halperin was able to establish the Kyiv district headquarters of the organization, which included Benzion Ginzburg, working in a hosiery workshop. The guy led the city organization Hashomer Gatzair and actively involved new members in the Jewish national movement.The outstanding organizational skills of Benzion Ginzburg did not go unnoticed.

At the end of September 1928, an order came from the "Hashomer Hatzair" headquarters in Moscow to send Joseph to Belarus. This tactic – sending activists to other republics – was used by all underground movements. Before leaving Kyiv, Benzion went to Moscow for instructions from members of the Hashomer Hatzai General Staff, Fima and Sasha, who were known to him. He knew Fima from Kyiv, but saw Sasha for the first time in the Soviet capital. Sasha represented the Zionist Labour Party (ZLP), which by autumn 1929 was leading the right-wing youth movement.

It was rumored that Sasha worked as a gynecologist in one of the Moscow polyclinics, although no one had accurate information about him. Sasha, who was very careful and smart, managed to keep complete secrecy. Sasha and Fima gave serious tasks to their young colleague. In Belarus, they needed him to contact left-wing Zionist organizations.

Their main goal was to attract all members of the "Class" youth movement to the right-wing side of Hashomer Hatzair, which professed Marxism and Zionism. If he failed in his main mission, he should at least agree on unity of action between right- and left-wing Zionists. In addition, he also had to restore cells in Gomel district where the organization's work had failed completely.Ginzburg failed to create a block between the left-wing and right-wing "Shomer" organizations. When Benzion finally approached the participants of the class organization, they did not want to hear about a block, considering the ZLP and right-wingers Hashomer Hatzair organizations as bourgeois. The emissary managed to make some progress in Unech, Bragin, Rechitsa and other places in south-eastern Belarus. Finding a local asset, Benzion encouraged his comrades greatly and helped to recreate several fairly strong Zionist groups. Tova Rubman recalled that Benzion Ginzberg was a cheerful and cheerful young man, and a very dedicated comrade. No one could imagine what a hard and dangerous job he did. When he lectured, people were amazed by his calmness and ready to work with Jewish youth again.Having completed his mission in Belarus, Benzion Ginzburg was sent to Vinnytsia in early 1929 as the head of the Podolsk district headquarters of "Hashomer Hatzair". Arriving in the city, he went straight from the train station to the Vinnytsia Pharmaceutical College, where Maryam was studying. Maryam, who was actually named Rachel Rapoport and was a member of the Podilsk district headquarter, managed to survive after the defeat of the Vinnytsia organization and the arrest of its chief of staff Grisha Cherny. Calling the girl into the corridor of the college, Benzion said: "Greetings from Fima!"

Maryam immediately recognized who was in front of her and agreed to help Benzion connect him with David, a young man who had survived the mass arrests and who was also a student at the Vinnytsia Construction and Reconstruction College. From these three young men at the beginning of 1929, a new Podolsk district headquarters of "Hashomer Hatzair" was formed. At that time, the work of the right-wing Zionist underground in Podillia had practically ceased. In order to revive the organization's activity and show that Hashomer Hatzai lives and works, Ben Zion Ginzburg organized the publication of an illegal magazine called Al Hamishmar (Hebrew for "On Guard").The magazine was published in Hebrew and printed on a Shapirograph, which was kept in a secluded place by Rachel and Gedal. During Benzion Ginzburg's stay in Vinnytsia, 3 or 4 issues of the magazine were published, with a circulation of 20-25 copies each. It was calculated that each group would receive one copy of the magazine. Rachel Rapoport obtained the chemicals for the Shapirograph. The head of the Podol district headquarters was involved in the production and editing of the magazine himself. Benzion rented a room next to Vinnytsia prison and set up an underground printing press there. The landlord suspected that something illegal was happening in the room, but he preferred to charge an exorbitant rent and turn a blind eye towards Ginzburg.The publishing work went so well that the district headquarters decided to issue a newsletter called "Izvestia" every two weeks.

Izvestia covered life in Palestine and the situation of Jews who had left for Eretz Israel, as well as touching on the problems of Jewish youth in the Soviet Union. Zionists drew materials for the bulletin from newspapers and magazines published in Mandatory Palestine.At that time, the national labor organization "Hashomer Hatzair" faced a question: in the towns which were the main source of replenishment for the organization, the social base of the movement was beginning to decline sharply due to unemployment. Young Jews, driven by unemployment, sought to leave for industrial centers in order to acquire some kind of qualification. Considering this, the leadership of Hashomer Hatzai decided to move the "center of gravity" for the Zionist movement to larger cities where Jewish youth were concentrated. In order to strengthen the backbone in these cities, it was decided to establish Shomer Gdudas ("labor leagues") in Kyiv and Moscow consisting of promising young Zionist activists. While driving around the villages and towns of Podolia, Benzion Ginsburg simultaneously looked for people for Moscow's Gdud, sending the most active Zionists from his towns to Soviet capital. Malka Esrig, Hana Rozen, Michael Glazer and Moishe Yospe were sent from Kupel and Kupin respectively.Having restored the activities of Hashomer Hatzair in Podol, Benzion Ginsburg was again sent to Kyiv. There, within a very short period of time, he managed to organize two large groups of "Shomers", each numbering 20 members: the city group and the Podil group. However, he did not remain in Kyiv for a long time. Benzion believed that, in order to operate on a countywide scale, it was necessary to raise the general literacy of the population. He wrote to the General Staff of Hashomer HaTzair asking for permission to enroll at an educational institution. Soon, he was summoned to Moscow. The head of the General Headquarters, Boris, recently returned from exile, told Ginsburg that the leaders of the movement had planned to set up courses for the Shomer asset, and Benzoin enrolled in these courses.The main headquarters of Hashomer Hatzair, however, did not have its own resources to organize courses, so it was created jointly with Tarbut, an educational and cultural organization that had been outlawed for a long time in the Soviet Union. Tarbut managed to find money and necessary literature, specifying Hebrew knowledge as a prerequisite for admission to courses. Benzion joined one of two training groups, along with his friend Michael Glazer and Israel Lisenberg. Hillel Kaplan and another girl also joined. Benzion and Israel settled in the Moscow area, at one of the northern railway stations. Glazer and Kaplan lived closer to the city on Perlovka Street, and the girl lived in Moscow.The courses began in May 1930, and prominent "tarbutniks" became their teachers.

However, the young Zionists were not satisfied with the courses. Benzion Ginzburg and his comrades wanted to gain more knowledge about Zionism, while the lecturers taught courses mainly in general education subjects. After a while, the students even raised the question of the expediency of such an education. While the discussion was going on, the arrests that began in Moscow put a bold cross on the courses.Changes have also begun in the "Shomer" organization. It was still considered an organization for children and teenagers, but all its main participants were already adults. Benzion Ginzburg and other "Shomers" felt it necessary to document this change from a children's and adolescent organization to a youth organization. In addition, they needed to determine the future program of work and decide on the organization's relationship with the merger of the Hitahdut Party in Palestine, known as the ZLP, which the right-wing "Shomers collaborated with, and the left-wing Zionist party Poalei Zion. This collaboration led to the formation of Mapai, a party that later governed Israel for many years.

The All-Union meeting of "Hashomer Hatzair" was held on December 21, 1930 in Moscow. The meeting was attended by: the head of the main headquarters Boris, Buzya Tepelboim – the leader of the movement from Odessa, Moishe Lempert – from Belarus, Hillel Kaplinsky, Avrum Shoikhet and Benzion Ginzburg – from the activist courses, Abraham Halperin – a representative of the Podolsk headquarters, Abraham Greenberg – from the Moscow Gdud.

The meeting documented the transition of "Hashomer Hatzair" into a more adult movement, renaming the organization the "Zionist-Socialist Youth Union". Boris, Abraham Halperin, and Buzya Tepelboim joined the Central Committee of the "Zionist-Socialist Youth Union". Benzion Ginzburg was elected as a candidate. The Zionists present reaffirmed the stance that the center of gravity of the movement should be shifted to industrial cities, where Zionist youth were actively gathering. The meeting also confirmed that the primary goal of the organization would be the struggle for the repatriation of Jewish youth from the USSR to Eretz Israel. There could no longer be any talk of any political or cultural struggle within the Soviet Union.

To implement the decisions of the meeting on the creation of Gduds in large industrial centers, the Central Committee of the "Zionist-Socialist Youth Union" decided to send Benzion Ginzburg to Gomel. He was well acquainted with the local conditions. Moreover, he was too prominent a figure in Moscow and Ukraine. Ginzburg came to Belarus under a new name – Rosentul Mendel Ikhilevich. That was the name of his neighbor from Lyantskorun, who had left the town long ago. The real Mendel was considered a bit strange in the town, had no interest in politics at all, and Benzion could easily provide details of his countryman's biography in case of arrest.