

CreditCreditRina Castelnuovo for The New York Times

JERUSALEM — Most of the mourners had never met Nate Remer, who survived the Holocaust hiding in a Ukrainian forest, built a successful wholesale hardware business in Southern California and had severe dementia for 15 years before dying Tuesday at 82. They did not know his son, Gary, a professor at Tulane University, or his grandson, Moshe Alexander, who moved to Israel five years ago and works in high tech.

They came, anyway, to the hilltop funeral on Thursday, Holocaust Remembrance Day. There was Ben Pask, 29, a lawyer who took the day off because he had returned to Israel at 5:30 a.m. from the United States. There was Jessie Schechter, 59, who hurried to finish her pre-Sabbath shopping to make the 4 p.m. service, and brought a friend.

There was a busload of yeshiva boys; a paramedic-firefighter visiting from Tampa, Fla.; and Julia Spiegel, 18, who had never been to a funeral. Many had seen a Facebook post expressing concern that there might not be a minyan, the quorum of 10 required for the Jewish mourning prayer.

In the end, there were about 150 people in the small chapel on Jerusalem’s Mount of Rest, many of whom stayed to form two lines and envelop family members as they walked away from the fresh grave.

“I just want to be here,” said Ms. Spiegel, who is from Memphis, Tenn., and is spending the year between high school and college in Israel. Her grandfather, Martin Koby, is a Holocaust survivor, too: He was a teenager then in Poland. “It’s important for people to have their proper burial,” she added. “This is a special day for that, in general.”

Thursday morning, more than 500 strangers responded to a similar Facebook call to fill the funeral of Benjamin Schlesinger, another 82-year-old Holocaust survivor, in the southern Israeli city of Ashdod. On Monday, hundreds were lured by social media to another cemetery to honor another survivor, Haya German, 92, who endured medical experiments at Auschwitz and never had children.

Holocaust Day is a major event in Israel. Much of the country stood silent for two minutes after a siren sounded at 10 a.m. Television channels broadcast only Holocaust-related documentaries the night before, or simply showed flickering candles. Spinning classes were canceled at Studio Mati, a gym near the Malha Mall in Jerusalem, because upbeat music is forbidden; the radio was filled with mournful melodies instead.

If attending a survivor’s funeral on Holocaust Day felt like destiny, mourning strangers is not an isolated phenomenon here. Some 30,000 people showed up last summer to bury Max Steinberg, 24, an American who had volunteered for the Israeli Army and was killed fighting in the Gaza Strip.

Even as Mr. Remer’s service ended on Thursday, thousands were pouring into the same cemetery for the funeral of Shalom Sherki, 25, who was killed the night before by a Palestinian driver who slammed into a bus stop in the East Jerusalem neighborhood of French Hill.

“It’s a Jewish thing, you know?” explained Ms. Schechter, a photographer and video editor who moved to Israel from Miami 25 years ago, citing the mitzvah, or commandment, to escort the dead. “One of the principles we stand on is you do things in this world that there’s no reward for in this world. The sweetness of it, the reward, is in the world to come.”

She and others said they were particularly moved by the short summary of Mr. Remer’s story that they had seen on Facebook. His father died while they were hiding in a stable in the Ukrainian forest, and he and his brother risked their lives to bury him. Some 40 years later, Mr. Remer returned to that forest, twice, to find his father’s remains. They were reburied in Jerusalem; now the son lies nearby.

Thursday’s service was simple. Gary Remer, an associate professor of political science at Tulane, told of how his father had made sure to call him and his sister every night, a reflection of the family’s insistence on moving as a group throughout the war. Mr. Alexander recalled his grandfather as “a great dresser,” with “more shoes than anyone else.”

At the graveside, Harvey Grossbard, another relative, remembered a visit to a Lower East Side art gallery, where the clerk recognized Mr. Remer’s accent and the two discovered that they had grown up a block apart in Yabluniv, Ukraine. “They both thought they were the only one who survived,” Mr. Grossbard said. “It was a tremendous moment.”

Besides his son, Gary, Mr. Remer, who lived in Los Angeles and owned the Remco Wholesale Hardware Company in the City of Commerce, is survived by his wife of 59 years, Jacky; a daughter, Rebecca Alexander, who lives in New Jersey; six grandchildren; and three step-grandchildren.

Mr. Grossbard’s wife, Janet, connected far-flung family members to the funeral via FaceTime on her smartphone.

“Well, Moshe, you have your minyan,” she told Mr. Alexander, 22, after the service. “You were so worried.”

A version of this article appears in print on , Section A, Page 18 of the New York edition with the headline: Helping to Mourn a Holocaust Survivor. Order Reprints | Today’s Paper | Subscribe