THE HAGUE — The choreographer Alexei Ratmansky was leading a newly formed ballet company of Ukrainian dancers who have fled the war in a run-through of “Giselle,” a 19th-century classic, in a repurposed conservatory here where the dancers have been rehearsing, and some living, since April.

He seemed to be everywhere at once, fine-tuning the corps de ballet, correcting a soloist, and honing the acting of a male lead. He was working to turn this ad hoc group of dancers of varying skill into a first-class company that could project Ukrainian excellence to the world.

Ratmansky, one of the greatest living choreographers and most important figures in ballet, has thrown himself into supporting Ukraine, where he spent his childhood, with an intensity matched by few other artists. When the Russian invasion began, he was in Moscow working at the Bolshoi Ballet, where he was once the artistic director; he left immediately and later said he was unlikely to return while President Vladimir V. Putin remained in power in Russia.

On social media he has marshaled expressions of solidarity with Ukraine from across the ballet world, a world in which Russia has historically played a towering role. And he and his wife, Tatiana, a former dancer, spent two months in The Hague, helping build the new United Ukrainian Ballet Company, which toured the Netherlands and performed in London.

It is a major shift for Ratmansky, who has said in the past that he did not see himself as a political artist. But since Russia invaded Ukraine, he has begun to see things differently. “The situation brings art and politics together in such an obvious way, in a way I’ve never experienced before,” he said.

The choice of “Giselle,” a French ballet, reflects this. “We picked it because it is something that they know, and that requires a large number of dancers,” Ratmansky said, “but also because it is not Russian.”

Ratmansky’s life and career reflect the long, intertwined relationship between Russia and Ukraine. With a mother from St. Petersburg and a father from Kyiv, Ratmansky grew up in Kyiv, trained in Moscow, and began his dancing career at the National Ballet of Ukraine. As a student in Moscow, he was often referred to as “the boy from Kyiv.” After stints in Canada and Denmark he became a choreographer and rose to the heights of Russian ballet, becoming the director of the Bolshoi, before leaving in 2008 to become artist in residence at American Ballet Theater in New York, and to focus on his increasingly busy international career.

Since the invasion, he said, he has heard from few of his Russian friends and colleagues, though many know he has family in Ukraine. “It’s hard to put into words,” he said. “It is very painful.”

In The Hague, Ratmansky — who, like many Ukrainians grew up speaking Russian — reluctantly led rehearsals in Russian. “I was hoping to switch to Ukrainian while I was here but when I tried I made so many mistakes, the dancers were all laughing,” he said.

Ratmansky’s parents, Osip and Valentina, both in their 80s, were able to leave Ukraine to visit him briefly in The Hague, taking a long bus ride to Warsaw and then a flight to Amsterdam; they hadn’t seen their son since the invasion. “My parents were their usual selves,” he said. “Apart from just being bubbly and hugging us they were like professional tourists, trying to see as much as possible.” After a week, they returned to Ukraine. “We had one or two more serious talks,” he said. “Of course it hasn’t been easy.” They insisted that they would be fine.

The new company was formed through the efforts of Igone de Jongh, a former star of the Dutch National Ballet, who was on tour with two dancers from the National Ballet of Ukraine, Alexis Tutunnique and Stanislav Olshanskyi, when the war began. With the help of the Dutch theatrical management and production company Senf and city officials, she became the leading force behind the establishment of the Dutch Center for Ukrainian Dancers here, and began working to create the United Ukrainian Ballet Company. Word of the new company spread quickly, via social media, among the Ukrainian ballet diaspora.

De Jongh knew Ratmansky from her time at Dutch National, where she danced several of his ballets, including “On the Dnieper” and “Russian Seasons,” but did not know his background until she began to see his full-throated support for the Ukrainian war effort.

When she invited him to help the new ensemble, he jumped at the chance, agreeing to donate his time. In less than two months, a company was born.

Ratmansky arrived in June to begin rehearsing his “Giselle,” which is based on archival documents, including 19th-century notations. Sets and costumes were lent by the Birmingham Royal Ballet, with the second-act backdrop, a nocturnal forest, borrowed from Frederick Ashton’s “The Dream.” When the company tours London, the English National Opera will provide an orchestra, to be led by Viktor Oliynyk, who conducts the orchestra of the National Opera of Ukraine in Kyiv, where the Ukrainian ballet also performs.

During a recent visit to the former conservatory, small groups of dancers, who come from Kyiv, Odessa, Donetsk, Dnipro and Kharkiv, and range in age from 18 to their late 30s, went about their business with a quiet sense of purpose. A few huddled on couches, speaking in soft voices in a mix of Ukrainian and Russian. The children of several dancers (there are 63 dancers in all) and of some of the nearly 200 other Ukrainian refugees living in a separate wing of the building, ran through the hallways, making up games.

At first, there were only women at the conservatory, since men of military age are not allowed to leave Ukraine. But to make it possible for the company to perform larger works, the Ukrainian Ministry of Culture has given temporary permits for male dancers to travel to The Hague, since the company’s performances will promote Ukrainian culture abroad.

Some, finding the separation from family too difficult, have returned home already.

The conservatory’s classrooms have been converted into makeshift dorm rooms, each housing up to four people. Bathrooms and kitchens are shared. Amenities are basic, but many of the dancers spoke of the solace they felt at having landed in a place where they could live among other Ukrainians and finally get back to routines they have followed since they were children.

The thing that anchors their life is ballet. The sound of music streams out of dance studios where, every morning, from 11 to 12:15, the denizens of this self-contained and orderly world engage in the universal dancers’ ritual: morning class.

On a Sunday in late August, a Dutch ballet master they have been working with, Rinus Sprong, led a company class outdoors, in front of the Russian Embassy — ballet class as civil protest.

“I want people to see them as artists, not as refugees or victims,” Ratmansky said after a rehearsal. “There is so much history and drama behind these performances. It colors everything we do.”

With time and effort, the group has made great strides, the Ratmanskys agreed. And there is something special about their dancing, they said. “Compared to their Russian colleagues, who are overwhelmed by rules of how to behave onstage,” said Ratmansky, “they’re more free and a bit more down to earth, more alive.”

This was borne out at the first tryout performance of “Giselle,” at Alphen aan den Rijn, a small city about half an hour from The Hague, on Aug. 13. When it ended, after their bows, the curtain opened once more and the dancers, some still in their costumes, others wearing street clothes, sang the Ukrainian national anthem. Ratmansky held up a large Ukrainian flag. People in the audience and onstage were moved to tears. On the bus back to The Hague, the dancers listened to Ukrainian songs. Many sang along.

“It is,” he said, “a little bit like a return.”