LVIV, Ukraine — After Russian forces surrounded the town of Mariupol in southern Ukraine, slicing off its water and gas and stopping assist convoys from coming into, Yulia Beley sheltered in a neighbor’s basement along with her three daughters and struggled to outlive.

Her husband was off defending the town, so she ventured out as bombs rained right down to fetch water from a distant nicely and tried to consolation her youngsters whereas the shelling shook the partitions and ceiling. In time, the household’s meals dwindled and Ms. Beley, a baker, mentioned she fed her hungry youngsters one bowl of porridge a day to share between them. Her 6-year-old daughter, Ivanka, dreamed of the poppy seed candy rolls her mom had made earlier than the warfare.

“It tears you aside,” mentioned Ms. Beley, 33, nonetheless traumatized after her escape from the town per week in the past. “I simply sobbed, simply cried, screaming into the pillow when nobody might see.”

Shortly after Russia invaded Ukraine, it laid siege to Mariupol, utilizing the traditional warfare tactic to attempt to starve the once-bustling metropolis of 430,000 folks into give up.

From the times when armies surrounded medieval castles in Europe to the battle of Stalingrad in World Struggle II and the squeeze placed on insurgent communities in Syria throughout the 11-year civil warfare, militaries have used sieges all through historical past whatever the catastrophic results on civilians caught within the center.

This month, Secretary of State Anthony J. Blinken accused Russia of “ravenous” cities in Ukraine. He invoked the reminiscence of the brother of President Vladimir V. Putin of Russia, Viktor, who died in infancy throughout the German siege of Leningrad throughout World Struggle II.

“It’s shameful,” Mr. Blinken mentioned. “The world is saying to Russia: ‘Cease these assaults instantly. Let the meals and drugs in. Let the folks out safely, and finish this warfare of selection towards Ukraine.’”

Students of siege warfare say the tactic serves totally different functions: to weaken enemies whereas avoiding clashes that may kill the besieging pressure’s personal troopers, or to freeze energetic fronts whereas attacking forces reposition. However the grueling nature of sieges — and the way they use starvation to show folks’s personal our bodies towards them — offers them a psychological energy distinctive amongst warfare techniques, based on students and siege survivors.

Depriving a residential space of meals whereas bombarding it serves not solely to flush out combatants, she mentioned, however to speak to everybody trapped inside: “You aren’t an equal human to me. You don’t should eat, drink, have drugs and even breathe!”

After they surrounded Mariupol final month, Russian forces lower off the town from the whole lot it wanted to reside, the mayor, Vadym Boychenko, mentioned on Ukrainian nationwide tv. In addition they destroyed the town’s energy vegetation, slicing off electrical energy for residents as temperatures froze, Mr. Boychenko mentioned, after which the water and gasoline, important for cooking and heating.

Some civilians managed to flee, making harrowing journeys via destroyed streets and Russian checkpoints. However about 160,000 persons are believed to nonetheless be trapped inside the town, Mr. Boychenko mentioned, and greater than two dozen buses despatched days in the past to evacuate them had not been capable of enter the town due to Russian shelling.

On Monday, the Worldwide Committee of the Purple Cross mentioned it was ceasing reduction operations in Mariupol as a result of the combatants couldn’t assure the protection of assist staff.

Nearly 5,000 folks, together with about 210 youngsters, have been killed there, the mayor estimated, however the figures couldn’t be confirmed due to the issue of getting data.

Russian forces are accountable for components of Mariupol, President Volodymyr Zelensky of Ukraine instructed a gaggle of impartial Russian journalists on Sunday. However the middle of the town continues to carry, based on Ukrainian and British navy assessments.

An aide to the mayor, Pyotr Andryuschenko, instructed The New York Occasions that an estimated 3,000 Ukrainian fighters from the Azov Battalion had been defending the town towards about 14,000 Moscow-backed troopers.

When the siege started, one Mariupol resident, Kristina, mentioned she, her husband and two youngsters camped out within the entryway of their constructing, hoping it will present higher shelter and safety than their residence.

Her husband, a enterprise analyst, ventured out to search out water and he or she cooked on an open hearth. In addition they collected rainwater and snow, boiling the water to sterilize it.

She learn fairy tales to attempt to distract the kids, however as soon as they acquired hungry, “the fireplace was gone from their eyes,” mentioned Kristina, who didn’t wish to use her full identify for worry of retribution. “That they had no real interest in something.”

“We ate as soon as a day,” she mentioned. “It was principally within the morning or within the night that the kids cried out, saying, ‘I wish to eat.’”

Her household lastly fled the town, however left behind her father and grandparents. She has struggled to maintain tabs on them as a result of the town’s cellphone networks are principally out.

Final week, she mentioned, they despatched a textual content that learn: “No roof, no meals and no water.”

Medical doctors who examine starvation and hunger describe a grim technique of the physique mining itself to remain alive. First, it burns glucose saved within the liver, then fats, then muscle.

Whereas dehydration can name kill in lower than per week, a well-nourished grownup can survive for greater than 70 days on water alone. Youngsters, the aged and the ailing succumb extra rapidly.

Different analysis has proven that hunger not solely weakens the physique however disturbs the thoughts.

Nancy Zucker, a professor of psychiatry and behavioral sciences at Duke College, mentioned analysis performed throughout World Struggle II on 36 male conscientious objectors who ate a low calorie weight loss program modeled on that given to prisoners of warfare confirmed they’d suffered “important psychological penalties.”

She added: “That they had hunger neuroses — elevated anxiousness, elevated isolation, elevated despair.”

That harm compounds in traumatic circumstances, like wars.

“That is hunger throughout a disaster,” she mentioned. “It is extremely exhausting to separate the profound psychological penalties from being in a state of warfare from these of not having sufficient meals.”

The reminiscence of starvation haunted the conscientious objectors within the examine lengthy after they’d regained their power.

“They wanted to be surrounded by meals,” and a few remained obsessive about it, she mentioned. “A number of went on to grow to be cooks.”

Irina Peredey, a municipal employee from Mariupol, mentioned that after she escaped, she was in such shock that she couldn’t eat for days.

After that, she started to crave a full meal about each hour.

“An hour passes and also you wish to eat,” mentioned Ms. Peredey, 29. “It appears to me psychological. You always begin consuming — and wish to eat as a lot as doable.”

At first she was confused, she mentioned.

“However now I see that apparently, that is how my physique is preventing again.”

As Ms. Beley, the baker, fought to outlive within the basement in Mariupol, she mentioned, bombs shook the constructing and shells had been so frequent that ever her daughter Aida, 3, realized to differentiate between incoming and outgoing hearth.

The household quickly ran out of meals. One other lady gave her a jar of honey.

“That’s how we survived,” she mentioned. “We didn’t have meals, however we are able to’t say we didn’t eat as a result of a spoonful of honey as soon as a day is already some form of lunch.”

When her household lastly managed to flee, she felt weak, like her physique was struggling to perform. Russian troopers provided sweet to her and her youngsters and at first, she refused. Then she modified her thoughts.

“Give me sweet, sugar,” she mentioned. “I noticed that I wanted one thing in order that I might keep myself.”

Valerie Hopkins reported from Lviv, Ukraine, Ben Hubbard from Beirut, Lebanon, and Gina Kolata from Princeton, N.J. Asmaa al-Omar and Hwaida Saad contributed reporting from Beirut.