The sculpture is 15 inches high.

The Wadsworth Atheneum Museum of Art in Hartford has made its most high-profile acquisition in more than a decade — a bronze sculpture by an Italian Renaissance master who stood among such giants such as Michelangelo, Donatello and Bernini.

Giambologna’s sculpture of the Roman god Mars is believed to be one of fewer than a half dozen in the world that were rendered by the sculptor himself and not subsequently by his students. The bronze is believed to have been made in 1580.

The Wadsworth wouldn’t reveal how much it paid for “Striding Mars,” but the nation’s oldest, continuously operating public art museum did say the list price was $4 million. The sculpture stands 15.5 inches in height and depicts the bearded god of war with penetrating eyes and captured in motion, emphasizing muscle and strength.

Jeffrey N. Brown, the museum’s chief executive, said the bronze will help bolster the Wadsworth’s European sculpture collection, which is not as advanced as the museum’s holdings of European paintings.

“This acquisition is a very strategic one for the museum, adding an extremely rare work by one of the great Renaissance sculptors to our collection,” Brown said. “With only a handful of castings known to have been done of this sculpture by the master himself, it is remarkable that one came on the market at all. It represented a once-in-a-lifetime opportunity and was only made possible by the use of a specific endowment fund that can only be used for the acquisition of art prior to the 18th century.”

The sculpture — purchased from a dealer — will go on display Thursday. The Wadsworth considered the purchase for over a year, consulting with researchers and conservators.

In a basement storage space at the museum this week, Vanessa Sigalas, the David W. Dangremond associate curator for collections research, can barely contain her excitement as she pulls on black, nitrile gloves and approaches the sculpture. The Roman god is perched on a recently made wooden mount adorned with marble medallions on each side.

Sigalas runs her finger along the sculpture’s thick mane of hair.

“When you look at these details, they are so soft, so fresh and evident — the toenails, the fingernails, the muscles,” Sigalas said. “These sculptures are really meant to be looked at from all angles.”

Striding Mars is representative of the Mannerist style, which evolved during the Renaissance. At its core, the style often includes exaggerated, lengthened limbs to convey an emotional effect.

Brown, who accompanied Sigalas on the visit to the sculpture, said the fact that Giambologna created this statuette is key to its significance because it retains all the details of Giambologna’s original wax mold.

“Having a Giambologna — he’s one of the most famous Renaissance sculptors. He was the person who brought bronze sculpture to a different level,” Sigalas said.

Second only to Michelangelo

Giambologna’s name may not be as recognized, but art historians credit him as being the most important sculptor during the Italian Renaissance after Michelangelo. Giambologna’s works often capture fleeting moments — such as catching Mars while walking — infused with drama and emotion, celebrating the human body. His sculptures can be described as lively, as if they are going to jump off their mounts.

Giambologna was born Jean de Boulogne in 1529 in what is now a portion of France. After already gaining renown for his art in France, he was drawn to Italy, where he was known as Giovanni da Bologna or simply Giambologna. He eventually settled in Florence and the powerful Medici family became his patron.

In his lifetime — Giambologna died in 1608 — he achieved renown throughout Europe with his works in bronze and marble. He traveled to Spain and England as well as the German states, where works such as Striding Mars were collected by royalty and connoisseurs.

Giambologna subjects ranged from mythological figures — such as Mars — to Christian and allegorical themes.

The Wadsworth said Giambologna refined the Renaissance depiction of the body, drawing directly from Michelangelo, whom Giambologna may have studied with as a young man.

Striding Mars is rendered in a battle-ready stance that grew in popularity in the second half of the 16th century, likely due to the Medicis’ preference for the figure as a symbol of Florentine authority.

Mars was modeled after a soldier Giambologna once spotted in a Florentine church, who stood 7 feet, 6 inches tall. The same model was used by the sculptor for his “Rape of the Sabines,” in 1581 and “Neptune,” rendered between 1563 and 1567 for a fountain in Bologna, Italy.

The bronze sculpture will be temporarily displayed in the Wadsworth’s Avery Court near the museum’s marble “Venus with a Nymph and Satyr” because of a connection between the two works of art.

According to mythology, Venus and Mars were lovers. But the Venus sculpture at the Wadsworth was created by Pietro Francavilla, who became one of Giambologna’s main assistants.

“So now, we have student and master together,” Sigalas said.