The man who commanded the clandestine operations that brought in four ships carrying some 24,000 illegal immigrants between 1945 and 1948, Yossi Harel, died yesterday in Tel Aviv at the age of 90.

The writer Yoram Kaniuk, a friend of Harel, told Haaretz that when the ships he commanded sailed past the coast of Turkey, Harel would think of the Armenian village in Franz Werfel's novel "40 Days of Musa Dagh," which described the Armenian genocide. "He loved the Armenian people and felt close to them," Kaniuk said, adding that he wanted to mention Harel's sensitivity to the Armenians as a sign of the great humanitarianism and compassion that were central to his Harel's character.

Harel was born in 1919, a sixth-generation Jerusalemite. He joined the Haganah at age 15 and later became part of the unit commanded by Orde Wingate, where he earned a reputation for bravery. Kaniuk related that David Ben-Gurion and Shaul Avigur (commander of the Aliyah Bet illegal immigration campaign and founder of Shai, the Haganah intelligence service) had marked him out as suitable to command the clandestine immigration ships because in addition to his leadership skills and fighting prowess, "there was something very hevreman [sociable] about him. He was not the kind of clap-you-on-the-back hero. He was a man of manners, the type who didn't raise his voice. He was a man of conscience and a daring fighter." He was also sensitive, and showed special care for women about to give birth on the ship, Kaniuk said.

Kaniuk also said, "Many of the sabras were snobs. They felt like heroes and did not show great sensitivity to the [Holocaust] survivors. It was hard for them to get in touch with their Jewishness. To Yossi, his Jewishness was important, as someone who had grown up in Jerusalem and not in Tel Aviv or on a kibbutz."

Harel commanded the major clandestine immigrant operations, including four ships: Knesset Israel, The Exodus, Atzma'ut and Kibbutz Galuyot. By the time he was 28 he had been responsible for about 24,000 immigrants had come in under his command, more than one-third of those smuggled into the country secretly between 1945 and 1948.

The Exodus, whose captain was Yitzhak "Ike" Aharonovich, went down in history for its heroic voyage from France in July 1947, carrying 4,500 Holocaust survivors, and the fight for months to keep it from being turned back by the British. Eventually the ship was forced back to Europe and sailed to Hamburg, Germany.

But the high point in Harel's career was not the more famous Exodus, according to an earlier article in Haaretz by historian Dr. Aviva Halamish. It was the two-and-a-half week voyage of the Knesset Israel. The ship set sail in November 1946 from Yugoslavia with 4,000 souls on boad. According to Halamish, this voyage brought to the fore the contrasts between the Yishuv, the Jewish community in pre-state Israel, and the clandestine immigrants, who were Holocaust survivors and "carried their struggle with them." Inspired by the story of the Knesset Israel, the poet Natan Alterman wrote in the newspaper Davar of the "division of labor" between the two groups.

Harel later went on to study mechanical engineering in the United States. He was called back by Israel Defense Forces chief of staff Moshe Dayan to command Unit 131, the intelligence unit that operated the Israeli spy ring that collapsed in Egypt in 1954. Eventually, Harel left the army and went into business.

Harel is to be buried tomorrow at Kibbutz Sdot Yam, near Caesarea.