The Smithsonian says this of the statue:
"Mills modeled Washington's portrait after Jean Houdon's famous and much copied bust of Washington. Mills served as the architect for this piece which was authorized by an act of Congress on January 25, 1853 and again on February 24, 1860. Mills had originally designed an elaborate base, complete with relief panels and additional figures of Washington and his generals, but due to a lack of funds, this base was not constructed.... The sculpture was temporarily moved during the early 1960s when the K Street underpass was built. It was reinstalled in 1963." -- SIRI
The Smithsonian further describes the statue this way.
"Equestrian portrait of George Washington dressed in his military uniform as he faces the British troops. The horse is rearing back, but Washington is sitting erect in the saddle as he looks out over the battle scene. His uniform consists of a long jacket with fringed epaulets, boots, and a three-cornered hat. He holds the horses reins in his proper left hand and his sword at his side in his proper right hand."
James M. Goode in Outdoor Sculpture of Washington, D.C., 1974 describes the statue this way.
"Clark Mills has captured a tense and crucial moment in the Revolutionary War in this early bronze equestrian statue of General George Washington. After months of retreat from the superior British armies in New York and New Jersey, Washington suddenly determined to gamble what was left of the American army on a surprise attack on the British forces at Princeton and Trenton. Washington is pictured advancing in front of the American lines toward the British, with shot an cannonballs exploding all around him. His stallion is terrified at the explosions encircling them; with open nostrils and bulging eyes the stallion refuses to respond to the command of his master.
Washington, whose face here is taken from Houdon's famous bust, a copy of which has always remained at Mount Vernon, is undaunted. He calmly holds the reins as he surveys the battle with unflinching determination. Mills has accurately sculpted the serenity and dignity of Washington's temperament. Both battles, in late December of 1777 and early January of 1777, were American victories; their principal importance was in rallying the flagging morale of the American soldiers and in holding the Continental Army together.
The Continental Congress first voted to erect a statue to Washington in 1783. On several other occasions, Congress voted to build various memorials to the beloved founder of the Republic. Unfortunately, however, nothing was completed until this statue was unveiled in 1860. Congress commissioned this statue in 1853 because of the tremendous popularity of Clark Mills's equestrian statue of Andrew Jackson, unveiled in Lafayette Park the same year. At that time, plans were made to erect the Washington statue just east of the Washington Monument which was then under construction. When it was finally unveiled a Washington Circle in 1860, it received much criticism because of the unnatural appearance of the horse and because the calm expression of Washington appeared incongruous with the terrified look of the horse. After guarding Washington Circle for over a century, this equestrian statue was temporarily moved to allow for the construction of the Street Underpass. In 1963, Washington and his horse were release from their wooden cage and returned to a familiar, if not refurbished home."
Both of the national illustrated weeklies, Harper's and Leslie's covered the unveiling and dedication of this statue on the eve of the Civil War.
Harper's Weekly Vol. IV, No. 166. Thursday, March 3, I860. Page 137.
Both papers noted that the plan was for the statue to stand atop an elaborate monument to Washington.
Harper's describes the planned monument that never came to fruition. The bottom half of the monument was to depict conflict with the Native Americans, the top half, conflict with Britain.
We engrave on the preceding page Clark Mills's Equestrian Statue of Washington, which is to be inaugurated on 22nd inst. at the federal Capital. It is proposed that the pedestal (which will be submitted for the adoption of the next Congress) shall be of marble, about twenty-five feet in height, to be divided into three stories, illustrating the three great epochs in the history of the country, the figures to be executed in bronze. The first story to represent the country as it appeared on its first discovery, when inhabited by the Indians; the second story, its general aspect under the changes wrought by the hand of civilization; the third and last story, the great revolutionary struggle -- to be surmounted by the colossal statue of Washington.The first story is seen in low relief. The Indian is represented as engaged in his favorite Sports - capturing the buffalo, pursuing the moose and deer, and cultivating his corn and tobacco. The first panel of the second story is in high relief. The white man appears cutting his way into the dense forest, with hope and prosperity beaming on his countenance. In a corner of the same panel, the Indian is seen retiring - looking wistfully back, loth to leave his hunting grounds, but obliged to fly before the face of civilization. In the second panel, the white man has cleared away the trees, erected his log cabin, and is cultivating his ground, symbolic of which are seen his oxen and plow. To show some of the difficulties which he bad to encounter here and there, from behind the trees, the Indian is seen shooting him down with the very rifle which the white man taught him to use. This leads to a war. The next panel shows the battle with the Indians - man to man, arm to arm- but the white man is represented as gaining the ascendency. The next presents the symbols of his progress in agriculture, commerce, and the arts, and his comparative power and independence. At this stage fresh difficulties arise, and these are the troubles with the mother country. The next succeeding panel exhibits the three shiploads of tea in Boston harbor, and white men, dressed as Indians, throwing the tea overboard. The next panel is the Signing of the Declaration of Independence. This brings us to the third epoch, the Revolutionary War.The third story is in full relief. Washington's Generals appear of the size of life. Eight of them are mounted on horseback; the rest are represented in groups, as if in consultation, holding a council of war.The crowning figure in this great historical representation is the statue of the Father of his Country, represented as be appeared at the battle of Princeton, where, after attempting several times in vain to rally his troops, he put spurs to his horse and dashes up to the cannon's mouth. His terror-stricken horse stops and recoils, while the balls tear up the earth beneath his feet; but Washington, cool, calm, collected, and dignified, believing himself simply an instrument in the hands of Providence to work out the great problem of liberty, remains firmly seated, like a god upon his throne. The repose of the hero at this moment of imminent peril to his life contrasts admirably with the fearful agitation manifested by his noble but unreasoning steed, who is sustained by none of the considerations which impart courage to the hero and the Christian. -- Harper's Weekly, Feb. 23, 1860.