[1] Banai was a senior Lehi member who masterminded numerous military encounters against British and Arab targets during the Mandate period and the 1947–1949 Palestine war.
On his way to Israel he was informed of the internal split within the Irgun and chose to join forces with Avraham Stern (Yair) to help form the Lehi.
Once in Israel he was ordered to distance himself from Tel Aviv to avoid the attention of the authorities and he enlisted as a watchman in the Jezreel Valley where he commenced forming a local branch of the Lehi.
In Haifa, Banai received the alias Mazal (meaning "Luck") after he managed to successfully evade capture during a surprise inspection conducted by British detectives.
Banai participated in a long list of combat missions including the preparations and attack on the British high commissioner in Palestine, Sir Harold MacMichael.
In his memoirs, Banai recalled that the order to assassinate Wilkin came directly from Yitzhak Shamir, the head of Lehi who eventually became the Prime Minister of Israel.
Banai authored the book Hayalim Almonim (Hebrew: חיילים אלמונים, "Anonymous Soldiers") based on his experiences in the Lehi.
[7] Banai frequently lectured to soldiers in the Israel Defense Forces, in schools, to youth groups, at community centers, and throughout the country.