Martin Johnson Heade began painting seascapes in 1858, after nearly two decades as a portrait and genre painter. The transition coincided with his move to New York City, where he established himself at the 10th Street Studio Building. While there he met and befriended Frederic Church, the celebrated artist of the Hudson River School. Impressed by Church's dramatic landscapes, Heade began experimenting in a similar style. However, he quickly abandoned many of the primary devices of the Hudson River School and developed his own distinctive Luminist imagery. Many of his works celebrated the quieter moods of nature. In these, often smaller canvases, Heade typically presents open landscapes or seascapes, usually with little human activity, in which he emphasizes reflective surfaces, seamless brushwork, and a meticulous attention to the effects of light and atmosphere (T.E. Stebbins, Jr., et al, Martin Johnson Heade, Boston, 1999, p. 12-13).
Painted about 1860-63, Marshes at Boston Harbor is among Heade's earliest seascapes. By the conventions of the day, its composition is exceptionally simplified. The dramatic effect of the work is further enhanced by its quintessentially Luminist composition, in which the sky fills the top two thirds of the canvas. Most of all, the painting celebrates light--on land, on water, and in the air--perhaps most emphatically as a streak of lavender, pink and orange light illuminating a solitary cloud overhead. Using a pronounced, horizontal format, further emphasized by the strong horizon line, Heade paints a landscape bathed in diffuse sunlight. Hazy air seems to fill the landscape, and suggests an effect of absolute calm at twilight. On the open expanse of marshes, a distant figure tends to a sailboat, which, though small, is the one compositional element of size included by the artist. In the further distance, a sail breaks the horizon, and nearer at hand, another figure sits in a rowboat. These figures are small elements in a larger landscape, and serve to emphasize the solitude of the scene, and Heade's masterful ability to simultaneously capture the grandeur and serenity of nature.