Civil War era sketch illustrating earthworks construction to prevent a night attack, Library of Congress.

General Overview

The ground plane has long been consciously shaped before, during, and after battle to provide cover and protection for soldiers. Today these forms, called earthen fortifications or earthworks, are broadly defined as any earthen structure excavated for military purposes.

Earthworks place a barrier between an army and its enemy, and in their most basic form consist of a protective embankment or mound of earth called a parapet and a ditch that supplies the earth to build the parapet. In some fortifications, the parapet may be reinforced by a facing material, such as wood, stone, brick or sandbags, which is called a revetment. The nomenclature associated with earthworks is varied—entrenchments, breastworks, fieldworks, trenches—as are their forms and purposes. As military technology advanced, the design and construction of earthworks responded by expanding in complexity to include numerous features such as batteries, gun emplacements, magazines, and dugouts. [ see: Diagrams showing fortification parts ]


Fort Stedman with grass cover, Petersburg NB, VA, NPS photo.

Earthworks surviving in today’s landscape range from low, eroded mounds to massive well-preserved forms with clearly articulated features. Erosion, the process whereby particles of soil dislodge from earthworks and are transported away, poses the greatest threat to their longevity. Over time, this natural action can completely degrade the resource. Therefore, management should always focus on erosion prevention, whether earthworks are covered in grasses or forest.

In the United States, numerous historic battlefields held by private, local, state, and federal jurisdictions contain remnant earthworks. The National Park Service (NPS), which manages military earthworks at numerous locations, has surviving examples from the French and Indian War, the Revolutionary War, the War of 1812, the War with Mexico, the Civil War, late nineteenth century coastal defenses, practice trenches from World War I, and Pacific Island sites from World War II. Often municipal parks seemingly unrelated to battle, such as Rock Creek Park in Washington, DC, Grant Park in Atlanta, and Point State Park in Pittsburgh, may also contain military earthworks because the boundaries of the park now include historic locations of strategic, logistic, or topographic importance and the original designers such as Olmsted Brothers or Ralph Griswold protected the earthworks and integrated them into the park’s original design.

Many state and local parks also actively manage surviving military earthworks. Internationally, Canadian agencies responsible for several World War I military sites associated with the Somme in France are taking active measures to preserve extensive earthen trench systems.

Ditch and parapet under forest cover at Richmond National Battlefield Park, NPS photo.

Management Context

The first American battlefield parks were created at the end of the 19th century to commemorate and preserve the landscape of the Civil War. Thousands of acres of battle-scarred terrain were set aside to honor and interpret the human drama of war. At the time of their acquisition, these battlefields were once again being farmed with the exception of areas where extensive earthworks survived. Except for earthworks in primary interpretive areas, most examples were allowed to "disappear" into regenerating woodland."

In 1933, the National Park Service (NPS) assumed active management of these and many other military historical parks as well as decommissioned coastal fortifications when the War Department by means of a presidential executive order transferred these sites to the park service. Like the War Department, interpreted earthworks managed by the NPS were cleared of woody vegetation and maintained in mown grass cover most often composed of lawn-quality turf grasses. In parks with extensive earthworks, many examples remained under forest cover because of the inability to provide regular maintenance. Without a uniform guide as to the best maintenance practices for earthworks, many cleared examples became severely eroded because of inappropriate maintenance operations, visitor trampling, the absence of a consistent vegetative cover, and other impacts.

The first coordinated attempt to assess the management of earthworks did not occur until the mid-1980s when the NPS conducted a study of military earthworks in four Virginia battlefield parks. This effort resulted in the Earthworks Landscape Management Manual (1989). The study found two conditions critical to earthworks preservation: first, to combat the destructive consequences of erosion, maintain a healthy vegetative cover on the earthworks with as little human intervention as possible. The study’s second important finding was military earthworks in forested conditions exhibited the least amount of erosion and contained the sharpest profiles and most legible features.

Typical field fortification and forms.

In 1995, NPS initiated the Guide to Sustainable Earthworks to further earthworks management research. Consultants on the project included experts in ecology, native plants, and forestry. Working independently in parks across the Mid-Atlantic and Southeast, the project team’s research supported the two major findings of the Earthworks Landscape Management Manual. Additionally, research indicated that a cover of native species, once established, could be equal to or superior to lawn-quality turf grasses for adaptation to the changing climate and conditions on the earthworks and, in the long term, should require the least human intervention.

Today, earthworks management is viewed as an evolving science that requires an integrated approach to natural and cultural resource management. Many parks in the public and private sectors employ a variety of techniques in an effort to expand the range of successful management practices.

Process for Earthworks Management

Military earthworks are often one resource within a larger park setting. A general planning document such as a master plan or a cultural landscape report typically establishes a historical context and an overall management philosophy.

This document identifies the management concept for the park as a whole and develops a management strategy for individual resources. For earthworks, a management plan ideally identifies key locations for visitor access, specifies interpretation strategies and themes, and determines in what condition earthworks are to be managed: grass or forest cover. Although specific approaches to earthworks management differ based on individual conditions, the following management fundamentals apply to every situation and are explored in detail in appropriate sections of this publication:


View from earthworks at Fort Sedgwick , Petersburg, Library of Congress.

1 Historical research informs the preservation planning process and is critical for decision making.

2 A thorough inventory of existing conditions and an accurate base map provide clear graphic information about the location, complexity, physical context, and condition of an earthwork or earthworks system.

3 Management planning, treatment, and implementation is essential in earthworks management and maintenance.

4 Resource monitoring establishes a baseline condition and measures the success of a management strategy.

Management Team

Earthworks management is a complex process requiring knowledge from a range of disciplines. Each phase of earthworks care, from background research to planning and implementation, requires a specialized interdisciplinary team to ensure the task is successfully achieved. Professionals associated with this effort include military historians, historical landscape architects, arborists, skilled maintenance professionals, cultural resource professionals, etc.

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