Haapalah / Aliyah Bet

While studying in London, where he met Ezer Weizmann, Boris Senior joined ITzL.
While in London, he also became involved in recruiting former South African Air Force veterans, and in acquiring aircraft from South Africa for Israel.

Hillel Daleski. was a Haganah recruit who had been in Palestine for only two months, when he was ordered to fire the artillery cannon that destroyed Altalena.
Machal.org.il cites: "Hillel (Billy) Daleski. Billy, an expert artillery man who had served with the South African Defense Forces in World War II, was commanded by Yitzhak Rabin who was in command of the Government troops, to fire at the Altalena. When Billy refused the order, he was threatened with a court martial and so he fired the mortar."
On June 20, 1948, David Ben-Gurion proclaimed in his Tutach HaKadish Holy Cannon Speech to the State Council: “Blessed be the cannon that bombed that ship!”

Yaakov Meridor was arrested for 10 days.

Yosef Nachmias, a company commander on board Altalena אלטלנה, cites: Menachem Begin, on the shore, said:
“Don’t fire back!” There will be no war between brothers! The first and second House of David was destroyed by brother hate ... There won’t be a destruction of the third House of Israel!”
Menachem Begin went out to Altalena אלטלנה, and from the command position of the bridge, and using loudspeaker saying - "Don’t fire back!” “Let them kill us all!” “We will never lift a hand on a Jew!”
He then sent Yoske Nachmias to negotiate, saying:
“Yoske - go ashore and with negotiation try to stop the fighting! You are going down without any arms ... You are going only with the ‘wireless’.”
Machal.org.il cites: "After the Altalena had run aground on the beach at Tel Aviv, the IAF was put on standby to attack the ship if necessary. Machal aircrews informed Aluf Aharon Remez, Chief of Air Force, that they would refuse to carry out such an order as they had not volunteered from abroad to fight against fellow-Jews, and that the Chief of Air Force had two options – either to court martial those who refused his order, or to discharge them from the service, and happily the standby order was promptly rescinded."
Yosef Nachmias cites: the refusal of his own brother, a Palmach fighter, to shoot at the ship because he knew that his sibling was on board, meant for him, that killing brothers was not merely a metaphor.
Jerold S. Auerbach cites: "Begin commanded his loyal fighters not to return fire. His insistence upon restraint demonstrated his unyielding determination to prevent civil war from once again dividing the Jewish people and shattering Jewish sovereignty, as it had done nineteen centuries earlier.”

Yosef Nachmias served in the ITzL אצ"ל company sent to unload the cargo aboard Altalena אלטלנה.
His brother was part of the Palmach פלמ"ח forces on the beach, and was ordered to shoot at Altalena אלטלנה, but, knowing that his brother was on the boat, he refused to shoot.

Yael Sherez, age 16 years old, was a Palmach fighter, who followed orders and shot at Altalena.

Boris Senior was ordered to bomb Altalena, but was enraged by the prospect and intended to drop the bombs elsewhere, but the mission was cancelled.

Hilary Dilesky, who had arrived in Israel only two months earlier, commanded the battery that was chosen to fire the first shot.
Hilary Dilesky cites: After receiving the orders, “I suddenly was struck with a heavy, deep feeling that I didn’t want to shoot.”
He told his corps commander, in English: “I hadn’t come to Israel to fight Jews.”
The commander responded that his job was to obey orders.
Hilary Dilesky cites: he realized that “following orders was the right thing to do, but my heart was broken when we began firing. This has been a burden all my life, and still is.”

Boris Senior flew a Spitfire from Czechoslovakia, and was forced to land at Rodos, where he was arrested by the British

Boris Senior is creditted with shooting down 2 Egyptian aircraft while serving in Israel's first fighter squadron.

Boris Senior was appointed the first Commander of the Sde Dov Airfield, and was a founding member of the 101 Air Squadron.