In classic Leonardo style and The Last Supper

In 1504, the Gonfalionere of Justice, leader of the Florentine Republic, Piero Soderini commissioned Leonardo da Vinci to decorate a wall in the newly built Hall of Five Hundred, the room where Florence’s Great Council met in the Palazzo Vecchio.

Whereupon Leonardo, determining to execute this work, began a cartoon in the Sala del Papa, an apartment in S. Maria Novella, representing the story of Niccolò Piccinino, Captain of Duke Filippo of Milan; wherein he designed a group of horsemen who were fighting for a standard, a work that was held to be very excellent and of great mastery, by reason of the marvellous ideas that he had in composing that battle; seeing that in it rage, fury, and revenge are perceived as much in the men as in the horses, among which two with the forelegs interlocked are fighting no less fiercely with their teeth than those who are riding them do in fighting for that standard, which has been grasped by a soldier, who seeks by the strength of his shoulders, as he spurs his horse to flight, having turned his body backwards and seized the staff of the standard, to wrest it by force from the hands of four others, of whom two are defending it, each with one hand, and, raising their swords in the other, are trying to sever the staff; while an old soldier in a red cap, crying out, grips the staff with one hand, and, raising a scimitar with the other, furiously aims a blow in order to cut off both the hands of those who, gnashing their teeth in the struggle, are striving in attitudes of the utmost fierceness to defend their banner; besides which, on the ground, between the legs of the horses, there are two figures in foreshortening that are fighting together, and the one on the ground has over him a soldier who has raised his arm as high as possible, that thus with greater force he may plunge a dagger into his throat, in order to end his life; while the other, struggling with his legs and arms, is doing what he can to escape death.
It is not possible to describe the invention that Leonardo showed in the garments of the soldiers, all varied by him in different ways, and likewise in the helmet crests and other ornaments; not to mention the incredible mastery that he displayed in the forms and lineaments of the horses, which Leonardo, with their fiery spirit, muscles, and shapely beauty, drew better than any other master.

In classic Leonardo style, he invented an accordion-folding scaffold to reach the top of his immense canvas. Also in a classic but less fortunate Leonardo style, he invented a new undercoat to apply to the wall under his oil painting. He didn’t want to use fresco because it had failed rather spectacularly in The Last Supper, so he scared up some weird mixture that in tests worked quite well. On the huge scale of the wall, though, where it was virtually impossibly to keep the environment evenly warm, the primer didn’t dry quickly enough and before his very eyes the paint started dripping. Leonardo brought in braziers to heat the wall and try to preserve what he could, but only the bottom of the painting managed to dry on time. The paints on the top were hopelessly intermingled. Bummed, Leonardo abandoned the project.
Even incomplete, the mural was widely revered. Many copies were made of it over the years, most notably by Peter Paul Rubens in 1603, based on a 1553 engraving by Lorenzo Zacchia. By the time Rubens made his version, Leonardo’s original was long gone. The Hall of the Five Hundred was enlarged between 1555 and 1572, and in the process The Battle of Anghieri and the incomplete work by Michelangelo that was across from it were both lost.