The war correspondent Martha Gellhorn wrote that war “happens to people, one by one,” which is true when you’re in the midst of it. But when you’re not, when the conflict is distant and abstract, war tends to happen one by the thousands. Reports of rising death tolls register but don’t resonate, and then, every so often, one person’s story transcends the numbing statistics.

Last week, just days after a UN official estimated that 400,000 people had died in Syria’s five-year civil war, Doctors Without Borders announced that an air strike on one of the hospitals it supports in Aleppo had killed more than 50 staff, patients, and nearby civilians, including Muhammad Wassim Mo’az, one of the only pediatricians remaining in the city.

There’s something particularly distressing about this story—about mourning the last pediatrician in a war zone. And on Wednesday, in The New York Times, a surgeon in Aleppo articulated what it is. His observation might seem obvious, but it’s also profound.

“Doctors and nurses are trying our best to put on a brave face for our patients,” Osama Abo El Ezz wrote. “We know that for the community we serve we represent a last hope, the final defenders of life in this city. But we are also among the fallen.”

In this case, Aleppo lost a final, stoic defender of children—many no older than the Syrian Civil War—whose lives are just beginning. When that last line of defense falls, what’s left? When a doctor dies, how many other lives are destroyed or stunted as a result?

“The effects of the attacks against health facilities emanate far beyond those immediately killed and injured,” Doctors Without Borders President Joanne Liu, a pediatrician herself, told the UN Security Council on Tuesday, in urging the world’s most powerful countries, and their allies, to halt attacks on medical facilities. Such attacks “demolish routine and lifesaving healthcare for all. They make life impossible. Full stop.”

One colleague described the 36-year-old Mo’az as a devoted doctor who by day worked at Aleppo’s Children’s Hospital and by night attended to emergencies at al-Quds Hospital, where he was killed. Several recalled the jokes Mo’az would tell patients and staff. He was “waiting for this bloody war to stop to be married,” one surgeon in Aleppo told the BBC. “He had to stay close to those babies. Who would treat those babies if everybody left?” Footage from security cameras in the hospital last Wednesday shows Mo’az leaving an intensive-care unit and heading toward the emergency room. He could have been in Turkey with his family. He could have taken the night off. Instead, he was walking briskly through the hospital’s dingy hallways in bright green scrubs. At one point in the video, he turns a corner and disappears from view. Moments later, the explosion comes.

“Day by day, we are bleeding our [medical] staff,” the surgeon told the BBC. “We will wait for a day [when] there will be no more doctors inside Syria.”

That day is near. Physicians for Human Rights (PHR), a New York-based NGO, estimates that more than 350 medical facilities in Syria have been attacked—largely by the Syrian military but also by Russian fighter jets and other armed groups—and that more than 700 medical personnel have been killed. Over half of Syria’s 30,000 doctors are thought to have left the country since the conflict began. In 2015, PHR estimated that 95 percent of doctors in Aleppo, Syria’s largest city before the war, had either fled, been detained, or been killed. Not a single psychiatrist or psychologist remained for a population deeply scarred by war. And this is just an accounting of health-care professionals, not of the poor condition of hospitals, or the acute shortages of medical supplies, or the excessive burdens placed on nurses, technicians, and medical students.

Syrian President Bashar al-Assad, a physician by training, has been fiercely battling rebel forces for control of Aleppo in recent weeks, threatening a brittle cessation of hostilities brokered by the U.S. and Russia. In the rebel-held part of the city, where Mo’az worked, there are now roughly 70 to 80 doctors treating 250,000 people, according to Doctors Without Borders. Last week’s air strikes also killed one of 10 dentists in the area, and left only six doctors at al-Quds Hospital.

In a recent report for The New York Times on his visit to the government-controlled side of Aleppo, Declan Walsh vividly illustrates the broader struggle in the divided city between the defenders of life and the prosecutors of death. He describes a boisterous, eerily normal wedding party where the music drowned out the sound of bombs exploding close by.

“There is war, and then there is life,” the best man at the wedding tells Walsh. “We have two hearts in this country—one for sorrow and one for happiness.”