In all, 164 people were killed in Mumbai and 308 were wounded. What stands out in the horror of those days is the particular viciousness of the attack on the defenseless people inside Nariman House. The Holtzbergs—a young couple, emissaries from the Chabad-Lubavitch movement—along with four other Jewish visitors were all killed. But Rabbi Gavriel Holtzberg and his pregnant wife Rivka were first tortured, the details of which are too gruesome to recount. (Their 2-year-old son was rescued by his Indian nanny, who grabbed the blood-spattered child and ran outside when the attackers weren't looking.)

Why did the attackers specifically target Chabad and why with such viciousness? Lashkar-e-Taiba, or the Army of the Pure, is South Asia's largest and most militant terror network. It is based in Pakistan, where it reportedly received planning assistance for the Mumbai operation from Pakistan's secret service agency. The group's founding aim was to reclaim the disputed Kashmir region for Muslims, but in recent years Lashkar has expanded to global scope, with particular animus toward India and Israel, declaring Hindus and Jews to be enemies of Islam.

Hence the attack on Nariman House, one of 3,000-plus Chabad Houses around the world that provide assistance, religious services, food, lodging and Torah study to local and visiting Jews. "Chabad," an acronym for the Hebrew "wisdom, understanding, knowledge," is another name for the Lubavitcher movement, named after the city in Russia where this particular movement of Orthodox Jewish Hasidism was founded in the 18th century.

Chabad would probably be unknown to the outside world had it not been for Rabbi Menachem Mendel Schneerson, its charismatic leader from 1951 until his death in 1994. Known as the "Rebbe" to his followers, he took a small group ravaged in the Holocaust and electrified it with a vision. Based in its new home of Crown Heights, Brooklyn, the Jewish movement grew rapidly, and today there are Chabad Houses from Morocco to Cambodia to Santa Fe.

While the Rebbe was a great Talmudic scholar, he was also an electrical engineer who studied at the Sorbonne and did work for the U.S. Navy during World War II. Perhaps because of his varied background, the Rebbe infused the Lubavitchers with entrepreneurialism. "This was not a man who was interested in creating followers," says Jonathan Sacks, the chief Rabbi of the British Commonwealth. "This was a man who was passionate about creating leaders."

Sending out emissaries was part of the program from the start, in 1951. "These extraordinary people could have achieved enormous personal gain in business or as professionals, but instead dedicated their lives to a higher purpose," says Rabbi Yehuda Krinsky, chairman of the movement's educational and social services arms.

Chabad's model sounds more like that of Christian missionaries than what most people expect of Jews. But Chabad couples are not sent out to proselytize. They are meant to act as role models for other Jews, in order to create a better world. Lubavitchers believe that every mitzvah (commandment) performed—whether it is helping someone in need or lighting the Sabbath candles—brings us all closer to the coming of the Messiah. "Love of God, of Torah and of every Jew—all three are really one and they cannot be separated," said the Rebbe upon assuming leadership of the movement in 1951.

Gavriel and Rivka Holtzberg were a typical Chabad couple—devout, devoted to the Rebbe's principles, and with a strong sense for self-sacrifice for their fellow Jews. They also suffered from personal tragedy. Their first child was born with Tay-Sachs disease, a genetic disorder that took his life at the age of two.

In another community, the violent deaths of such a young and promising couple might have sent shivers through the leadership, prompting them to pull other emissaries from the field. But Chabad's leadership did the opposite, immediately sending another couple to take their place.

"It was almost instantly reflexive for some, especially from knowing Gabi and Rivki," observes Rabbi Chanoch Gechtman, who together with his wife Leah now runs the Chabad House in Mumbai. "Great darkness must be challenged with bright light. WSJ. "