Michael Nagle for The New York Times

There are few images as enduring in American history as the one of General George Washington standing tall, next to the Stars and Stripes, in a rowboat gliding past mini-icebergs as he leads his troops across the Delaware River on Christmas Day 1776 to start a surprise attack on Hessian forces during the Battle of Trenton.

In his 1851 portrait, “Washington Crossing the Delaware,” among the best-known of American paintings, the artist, Emanuel Leutze, did not shy away from imbuing the scene with a dose of glory, inspiration and heroism.

He also did not let the facts get in the way of his masterpiece — the most famous version of his painting hangs at the Metropolitan Museum of Art.

The only thing wrong with this historical image is the history part, said Mort Künstler, as he recently put the finishing touches on his own version of Washington’s crossing. As it rested on an easel in Mr. Künstler’s studio on Long Island, the painting looked nothing like the Leutze version.

“I’m not knocking the original: it’s got great impact and Leutze did a heck of a job,” Mr. Künstler said. “I give Leutze higher marks for a good painting than for historical accuracy, but why can’t you have both?”

Mr. Künstler, who has gained some renown for painstakingly researched paintings that strive for accuracy, invested two months of research for the new painting, which is set to be unveiled at the New-York Historical Society in Manhattan on Monday, the date in 1776 that Washington led his troops into battle in Trenton after crossing the Delaware.

And so, instead of the small, somewhat tipsy rowboat in Leutze’s painting, Mr. Künstler depicts a 60-foot-long flatboat ferry, guided by cable, and crowded with dozens of troops, and cannons and horses.

Washington is not elevated, but rather nestled against a cannon wheel for support.

He is buffeted by driving snow — weather records show the crossing happened during a northeaster — and his face is lit by lantern and torch against a night sky. The ferry cuts through thick layers of ice, which Mr. Künstler says corresponds with the photographs he obtained of the actual way the Delaware freezes.

Leutze had limited access to historical material when he created the painting in Germany, where he was born. While Leutze painted a glowing sky and wide river, Mr. Künstler’s painting is more in keeping with the records that this was a dead-of-night crossing at a section of the river less than 300 yards wide. As for the flag in the Leutze painting — the Stars and Stripes was not adopted until after the crossing — Mr. Künstler’s version has no flag.

For all the differences between the paintings, Mr. Künstler was initially reluctant when offered a commission essentially to correct Leutze’s painting, a copy of which hangs in the White House.

“I said, ‘Are you kidding? That’s such an iconic image,’” Mr. Künstler recalled. “‘I’m not going to go against that. What can you do with it?’”

He said this to the man who commissioned him: Thomas R. Suozzi, a former Nassau County executive who also happens to be a Revolutionary War history buff.

Mr. Künstler countered with an offer to paint Washington on horseback on a bank of the Delaware instead, but Mr. Suozzi mustered his best lobbying skills to talk the reluctant Mr. Künstler into taking the challenge. He said he told Mr. Künstler: “No, I want him in the boat, I want to go up against the existing painting. The other painting is great, but it doesn’t tell the realistic story.”

The notion that Leutze created a romanticized version of a critical moment in American history is generally accepted by art experts.

“Leutze wanted to convey the idea of Washington’s heroism and to mythologize him, and you’re not going to do that necessarily by getting terribly hung up on factual information,” said Elizabeth Kornhauser, a curator of American paintings at the Metropolitan Museum of Art. “He was creating an operatic theatrical piece.”

Michael Nagle for The New York Times

A restoration of the painting was recently completed, and it will be unveiled in a new frame as the centerpiece of the New American Wing Galleries for Paintings, Sculpture and Decorative Arts at the Met when the wing opens to the public on Jan. 16.

A museum spokesman, Harold Holzer, said the Leutze painting was “the most asked-about picture at the Met.”

Mr. Künstler’s two months of research for the Washington painting included consulting historians and books, as well as journals about the crossing and weather records. He photographed the Delaware at the location — what is now called Washington Crossing — and researched the kinds of boats that were in use at the time.

Mr. Künstler has long tried to let history dictate his paintings, putting in months of research for a portrait. He has weighed Custer’s Last Stand and Theodore Roosevelt’s charge up San Juan Hill. With an estimated 5,000 paintings and ink drawings under his belt, he has done work that includes illustrations for National Geographic and movie posters for “The Poseidon Adventure,” as well as Mad magazine covers.

But, as Mr. Künstler said, “If I’m remembered for one painting, this will be it, simply because it is an iconic image.”

He was sitting at his work space, which is mounted on a large circular platform that rotates by motor under rooftop windows, to maximize the natural light. To help capture Washington’s likeness, Mr. Künstler taped a dollar bill to the canvas, and also kept a gift-shop statue of Washington nearby, as well as, yes, a copy of the Leutze painting.

Mr. Suozzi said he became fascinated with Washington’s crossing after reading the David McCullough book “1776” while running unsuccessfully in 2006 against Eliot Spitzer in the Democratic primary for New York governor. He said Washington’s heroism inspired him to stay in the race despite his dismal poll numbers.

“It was a heroic decision by Washington in a desperate and down time,” said Mr. Suozzi, a lawyer and investment banker. “And during my darkest days, when I had no shot of winning, it was the only thing that kept me going. I didn’t want to give up and not show my face. I was inspired by Washington to continue and keep pushing my property tax cap.”

Mr. Suozzi would not say how much he paid Mr. Künstler for his work, but Mr. Künstler said he charges $50,000 to $100,000 for a painting of this type. While the painting will be publicly shown for the first time at the New-York Historical Society, its permanent home is unclear.

Mr. Suozzi said that he planned to lend out the painting for public viewing, and that he was seeking an investor to finance a version of Mr. Künstler’s painting, which is about 4 feet wide and 3 feet high, that would match the size of the Leutze painting, which is about 21 feet wide and 12 feet high.

“I’m telling you,” Mr. Suozzi declared. “This painting will be the one they put in school textbooks one day.”

The Metropolitan Museum of Art/Art Resource, NY