The low block of this large fort is poised between sky and water, its tranquil reflection contributing to the pleasantly calm effect of Seth Eastman’s depiction. The sky is filled with gently animated clouds, and a sure handling of the space, from the darker, skillfully detailed foreground to the light-filled distance, marks the whole painting.
Fort Delaware was built on Pea Patch Island in the Delaware River, below Wilmington and New Castle, Delaware. The first fortification on the island was constructed soon after the War of 1812 to protect Philadelphia and its harbor as well as the dynamite and munitions plants near Wilmington. It was demolished in 1833. The present structure was erected between 1848 and 1859, becoming the largest fort in the country. During the Civil War, beginning in 1862, the island became a prison for captured Confederates and local Southern sympathizers. They were housed not in the fort proper but in wooden barracks that soon covered much of the island. Most of the Confederates captured at Gettysburg were imprisoned there. By August 1863, there were 12,500 prisoners on the island; by war’s end, it had held some 40,000 men. The conditions were predictably notorious, and about 2,900 prisoners died at Fort Delaware. Although the benign appearance of the postwar fort in Eastman’s painting might have seemed ironic to late 19th-century viewers, it is also true that Delaware’s guns never fired a shot during its entire history.
During the late 18th century and through much of the 19th century, army forts were constructed throughout the United States to defend the growing nation from a variety of threats, both perceived and real. Seventeen of these sites are depicted in a collection painted especially for the U.S. Capitol by Seth Eastman. Born in 1808 in Brunswick, Maine, Eastman found expression for his artistic skills in a military career. After graduating from the U.S. Military Academy at West Point, where officers-in-training were taught basic drawing and drafting techniques, Eastman was posted to forts in Wisconsin and Minnesota before returning to West Point as assistant teacher of drawing. Eastman also established himself as an accomplished landscape painter, and between 1836 and 1840, 17 of his oils were exhibited at the National Academy of Design in New York City. His election as an honorary member of the academy in 1838 further enhanced his status as an artist.
Transferred to posts in Florida, Minnesota, and Texas in the 1840s, Eastman became interesed in the Native Americans of these regions and made numerous sketches of the people and their customs. This experience prepared him for the next five yeas in Washington, D.C., where he was assigned to the commissioner of Indian Affairs and illustrated Henry Rowe Schoolcraft's important six-volume Historical and Statistical Information Respecting the History, Condition, and Prospects of the Indian Tribes of the United States. During this time Eastman also assisted Captain Montgomery C. Meigs, superintendent of the Capitol extension, in securing the services of several Native Americans to model for the sculptors working on the 1850s addition to the building.
In 1867 Eastman returned to the Capitol, this time to paint a series of nine scenes of Native American life for the House Committee on Indian Affairs. Eastman's talent and his special knowledge of the subject certainly qualified him for the commission, which was obtained for him by House Ways and Means Committee Chairman Robert C. Schenck of Ohio. Schenck, a former Civil War officer who, like Eastman, was retired for disability during the war, believed Amerian–-not European–-artists should recieve the Capitol commissions. In introducing a resolution urging the hiring of Eastman for the project, Schenck remarked:
We have been paying for decorations, some displaying good taste and others of tawdry character, a great deal of money to Italian artists and others, while we have American talent much more competent for the work. Among others . . . is General Eastman, who . . . is more of an artist in all that relates to the Indians, except possibly Catlin and Stanley, than any we have had in this country. . . . If assigned to this duty General Eastman will draw his full pay as lieutenant colonel, instead of as on the retired list, making a difference of about $1,200 or $1,500 a year. For at the most $1,500 a year we will secure service for which we have been paying tens of thousands of dollars to foreign artists, and we will get better work done. 
Schenck's resolution was approved by the House but tabled by the Senate. Nevertheless, the retired Eastman was placed–-by special order of the War Department–-on "active duty" so that he could be compensated for creating works of art for the Capitol. He finished the nine paintings in 1869.
In 1870 House Military Affairs Committee Chairman John A. Logan of Illinois proposed that Eastman produce 17 canvases depicting army forts. It is indicative of the post-Civil War sentiment in America that Logan specified that Eastman was not to paint battle scenes; indeed, the mood of these forts set in landscapes is serene, even nostalgic to some degree. Never a well man, Eastman was aged and ailing by the time he received the commission, and it is not known if he visited the forts. He had been stationed at several of these during his military career, and as a trained topographical draftsman he probably had plans, elevations, and even photographs of the forts at his disposal. Eastman completed the series between 1870 and 1875.
Charles E. Fairman, longtime curator of the Capitol, was slightly dismissive of Eastman's fort paintings. He thought they were "probably more valuable as examples of historical accuracy . . . than for purely decorative purposes."  He explained that it was important that knowledge concerning government fortifications should be easily accessible and these pictures "contain desired information and also relieve acceptably what might otherwise be blank spaces upon an uninteresting wall."  Yet without touting Eastman's paintings as masterpieces, it is still possible to value them as considerably more than repositories of "desired information."
For many years, the fort paintings hung in the House Military Affairs Committee Room, first in the Capitol and later in the Cannon House Office Building. During the late 1930s, they were returned to the Capitol for public display. Of the 17 paintings, eight are located in the Senate, while the others are displayed on the House side of the Capitol. Eastman was working on the West Point painting when he died in 1875.
1. Congressional Globe (26 March 1867) 40th Cong., 1st sess.: 362.
2. Charles E. Fairman, Art and Artists of the Capitol of the United States of America (Washington, D.C.: Government Printing Office, 1927), 239