Operation Agatha, sometimes called Black Sabbath or Black Saturday because it began on the Jewish sabbath, was a police and military operation conducted by the British authorities in Mandatory Palestine. Soldiers and police searched for arms and made arrests in Jerusalem, Tel Aviv, Haifa and several dozen settlements; the Jewish Agency was raided. The total number of British security forces involved is variously reported as 10,000, 17,000, and 25,000. About 2,700 individuals were arrested, among them future Israeli Prime Minister Moshe Sharett. The officially given purpose of the operation was to end "the state of anarchy" then existing in Palestine. Other objectives included obtaining documentary proof of Jewish Agency approval of sabotage operations by the Palmach and of an alliance between the Haganah and the more violent Lehi and Irgun, destroying the Haganah's military power, boosting army morale and preventing a coup d'état being mounted by the Lehi and Irgun.

The Jewish Agency for Israel, formerly known as the Jewish Agency for Palestine, is the largest Jewish non-profit organization in the world. It was established in 1929 as the operative branch of the World Zionist Organization (WZO).