Fighters from the Irgun and Lehi Zionist terror groups attacked Deir Yassin near Jerusalem, killing over 100 Palestinians.

The Irgun, officially the National Military Organization in the Land of Israel, often abbreviated as Etzel or IZL (אצ״ל), was a Zionist paramilitary organization that operated in Mandatory Palestine between 1931 and 1948. It was an offshoot of the older and larger Jewish paramilitary organization Haganah.

Lehi, officially the Fighters for the Freedom of Israel and often known pejoratively as the Stern Gang, was a Zionist paramilitary militant organization founded by Avraham ("Yair") Stern in Mandatory Palestine. Its avowed aim was to evict the British authorities from Palestine by use of violence, allowing unrestricted immigration of Jews and the formation of a Jewish state. It was initially called the National Military Organization in Israel, upon being founded in August 1940, but was renamed Lehi one month later. The group referred to its members as terrorists and admitted to having carried out acts of terrorism.

Zionism is an ethnocultural nationalist movement that emerged in late 19th-century Europe to establish and support a Jewish homeland through the colonization of Palestine, a region corresponding to the Land of Israel in Judaism and central to Jewish history. Zionists wanted to create a Jewish state in Palestine with as much land, as many Jews, and as few Palestinian Arabs as possible.

Deir Yassin was a Palestinian Arab village of around 600 inhabitants about 5 kilometers (3.1 mi) west of Jerusalem. Deir Yassin declared its neutrality during the 1948 Palestine war between Arabs and Jews. The village was razed after a massacre of around 107 of its Arab residents on April 9, 1948, by the Jewish paramilitary groups Irgun and Lehi. The village buildings are today part of the Kfar Shaul Mental Health Center, an Israeli public psychiatric hospital.