The British retaliated swiftly to the blowing up of the bridges by the Palmach. The following day British forces were sent to the Western Galilee to search Kibbutz Matsuba which was thought to be the base of the Palmach unit. Twenty-seven kibbutz members were arrested and sent to Acre jail. Searches were also conducted at Kibbutz Bet Haarava on the northern Dead Sea, on suspicion that it had served as the base for the group which attacked the Allenby Bridge. In the clashes with the soldiers, 12 kibbutz members were injured, two of them severely, and 70 people were arrested. The next day, military forces cordoned off Kibbutz Kfar Giladi in the north and when the soldiers broke in, the kibbutz members displayed passive resistance. Hundreds of members of nearby settlements hastened to their aid, and when they approached the kibbutz, the British troops opened fire on them. Three Jews were killed and six injured.

In total, four Jews were killed, eighteen injured and more than 100 detained in the operations carried out by the British after the Night of the Bridges. These events, however, were merely a prelude to the much larger operation which took place two weeks later and became known as Black Sabbath.

The action against the organized Yishuv, which had been planned carefully and in great secrecy, began in the early hours of Saturday, June 29, 1946. A countrywide curfew was proclaimed, and 17,000 soldiers entered institutions and settlements in order to confiscate weapons and documents, and to arrest leaders of the Yishuv and Haganah activists. The Mandatory government announced that it was determined to uproot terror and violence, and that the military action had been endorsed by the Cabinet in London.

Operation Agatha, as the British called it, took the Yishuv by surprise, and achieved most of its objectives. A considerable amount of intelligence information was collected, and thousands of Jews were arrested and jailed in a special internment camp which had been prepared at Rafiah. In Jerusalem, British troops entered the Jewish Agency buildings and, after ransacking the offices and in particular the archives, confiscated a large number of documents. This material was loaded onto three trucks and taken to the King David Hotel in Jerusalem, which housed the government secretariat and the military command. The documents included cables, which clearly demonstrated the role of the Jewish Agency in the leadership of the United Resistance. Also found was the text of the agreement between the Haganah and the Irgun and Lehi, and cables approving Irgun and Lehi operations against the British in the framework of the United Resistance. Another discovery was the text of broadcasts of Kol Yisrael (the Haganah's clandestine broadcasting station), stating, among other things, that everything possible would be done "to foil the transfer of British bases to Palestine and to prevent their establishment in Palestine".

Searching for Armes

In addition to the numerous documents confiscated from offices, the soldiers broke into the homes of members of the Jewish Agency Executive and arrested them.

At 4.15 a.m on the Sabbath, a police officer, followed by an army officer with two army vehicles, arrived at the home of sixty-year-old Rabbi Fishman-Maimon. The soldiers surrounded the house. Rabbi Fishman informed them that he was unable to travel on the Sabbath and proposed that he walk, or that the house be placed under guard until the Sabbath ended, when he would be able to travel. He asked the officers to consult their superiors on this proposal, but they had received orders to take him at once. Rabbi Fishman sat down and replied that he would not budge. The soldiers tried to carry him together with the chair, but the rabbi slipped off the chair, and they then took him by force and pushed him into the vehicle. Since there was no electricity because of the Sabbath, the soldiers used flash lights. (Davar newspaper, July 1, 1946)

Among those arrested were Moshe Shertok (Sharett) and Bernard Joseph (Dov Yosef) of the Political Department of the Jewish Agency, and David Remez, chairman of the Vaad Le'umi. Other public figures were detained all over the country and brought to the special VIP camp built for them at Latrun. In Tel Aviv, a thorough search was conducted at the Histadrut Executive and at the offices of the Davar newspaper and Bank Hapoalim.

Searches and arrests were also carried out in many kibbutzim, but the British had their greatest success at Kibbutz Yagur. The search there lasted a week, and the British apparently had prior information about the arms caches there. The kibbutz members resisted passively, but were dispersed by tear gas and incarcerated in enclosures set up by the soldiers. At first it was merely a routine search, but once the first arms cache was found, the British attitude changed, and the soldiers began to dig under the floors and in all possible hiding places in their search for arms. Their find included more than 300 rifles, some 100 2-inch mortars, more than 400,000 bullets, some 5,000 grenades and 78 revolvers. The loot was displayed at a press conference on the spot, and after arresting all the men of Yagur, the British withdrew.

Weapons found in Yagur

At Kibbutz Mizra, the British broke into Palmach headquarters, and confiscated a large number of documents, including the card-index of Palmach members. The names were written in code, and even though the British Intelligence did not succeed in deciphering them, the very fact that the list had fallen into their hands was a blow to morale.

During Black Sabbath, some 2,700 people were arrested throughout the country and taken to the Rafiah internment camp. Two days later, the Haganah command, headed by Moshe Sneh, convened to discuss retaliation. The opinion was that the armed struggle had to be continued in order to prove to the British that, despite the mass arrests, they had not succeeded in paralysing the United Resistance.

The Haganah command decided to carry out three operations against the British authorities. The first was a Palmach raid on the Bat Galim army camp, in order to requisition weapons (according to Haganah Intelligence Service information, the weapons confiscated at Yagur were being stored there). The second mission entrusted to the Irgun was the blowing up of the King David Hotel, where the offices of the Mandatory government and the British military command were located. The Lehi was allotted the task of blowing up the adjacent David Brothers building, which housed government offices. In a letter to Begin, Sneh wrote: (Jabotinsky Institute Archives, k-4 1/11/5)

a) At the earliest possible opportunity, you are to carry out the operation at the 'chick' (code name for King David Hotel) and at the house of "your servant and messiah" (code name for David Brothers building). Inform me of the date. Preferably at the same time. Do not reveal the identity of the implementing body - either by announcing it explicitly or by hinting. b) We too are preparing something - will inform you of details in good time. c) Exclude TA (Tel Aviv) from any plan of action. We are all interested in preserving TA - as the center of Yishuv life and the center of our own activities. If, as the result of any action, TA is immobilized (curfew, arrests), this will paralyse us and our plans as well. And the important objects of the other side are not focused here. Hence, TA is 'out of bounds' for the forces of Israel. 1.7.46. M. (Moshe Sneh).

While preparations for the operations were at their height, Meir Weisgal arrived at Sneh's hideout. Weisgal was on a personal mission from Chaim Weizmann, President of the World Zionist Organization (Weizmann himself was then ailing at his home in Rehovot). Weisgal told Sneh that Weizmann urged that the armed struggle against the British be halted. Among other things, Weisgal quoted Weizmann as saying:

In other countries it is accepted that the president is the commander in chief of the armed forces. I have never sought this authority nor has it ever occurred to me to interfere in your affairs. For the first and only time , I am exercising this right and demanding of you that you cease all this activity.

Weizmann demanded an immediate answer, and announced that if his request was rejected, he would resign and publicly announce the reasons for his resignation. Sneh, who was opposed to stopping the armed struggle against the British, informed Weisgal that he could not decide this matter alone, and would submit Weizmann's request to the X Committee. The Committee debated the question of the powers of the president of the World Zionist Organization, but eventually decided, by majority vote, to accede to Weizmann's request. Sneh, who opposed the resolution, resigned from his post as head of the Haganah General Headquarters, but remained liaison officer with the Irgun and Lehi. Sneh met with Begin, did not inform him of the X Committee's resolution, and merely requested that the assault on the King David Hotel be postponed. Sneh then decided to leave for Paris to attend a meeting of the Jewish Agency Executive, which was to discuss the continued struggle against the Mandatory government. Before leaving the country, on July 19, he sent Begin another note:

As a result of Sneh's appeal, the attack on the King David Hotel was scheduled for July 22, 1946. Because of coordination problems, the Lehi decided to cancel its plan to blow up the David Brothers building.

The X Committee was the supreme political committee to which were submitted the operational plans of the United Resistance (without specification of the target and exact date). The plans were implemented only after approval by the Committee.