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Often in danger, charting a path to Union's victory

Commemorating the 150th anniversary of the Civil War, NOAA’s Office of Coast Survey has dug into its archives and found a trove of wartime cartography and accounts of topographers and hydrographers dispatched to the front lines to work as surveyors, boat pilots, and chart- and mapmakers for the Union cause.

During the Civil War, Coast Survey field staff scouted, mapped, cleared sunken ships from channels and placed navigation aids to help Union forces.

Deployed in combat intelligence or combat engineering roles, Coast Survey field staff would scout, map, chart, pilot, clear sunken ships from channels and install navigation aids for Union forces, often while dodging bullets and artillery rounds.

“Most of the people in the Coast Survey were civilians,” Coast Survey spokeswoman Dawn Forsythe says. “They didn’t wear a uniform and could be summarily shot as spies. This was definitely a risk they faced.”
Unheralded, some of them died from wounds and many from disease contracted during the war, according to a National Oceanic and Atmospheric Administration history, “The Coast Survey.”
President Thomas Jefferson created the Coast Survey in 1807 to produce nautical charts for maritime safety and defense and to set national boundaries, but the organization nearly lost its funding to the Army and Navy at the start of the Civil War. Its superintendent, Alexander Dallas Bache, a great-grandson of Benjamin Franklin and one of the preeminent scientists of his day, saved the Coast Survey by turning its efforts to satisfy the Union forces’ appetite for maps, charts and surveys — and the local knowledge of its expert boatmen, says John Cloud, an historian who worked on the commemoration for NOAA.
“Some of the generals found these guys invaluable,” Cloud says. “They would go out [on reconnaissance patrols] and sketch out the battlefields and fortifications.”
Coast surveyor J.S. Harris’ sketch of Fort Jackson, a Confederate stronghold guarding the southern approach to New Orleans 32 miles from the Gulf of Mexico on the Mississippi River, still stands as a “work of art,” Cloud says.
What had started out as a reasonably quiet line of work had turned very dangerous. Sketches were produced under battlefield conditions, with mapping or charting teams often going out at night behind enemy lines to map terrain or take soundings or put out navigation aids for naval operations the next day.
Being federal employees, coast surveyors working below the Mason-Dixon line when South Carolina seceded found themselves in jeopardy. F.H. Gerdes, leader of a survey party in Pensacola Bay in the Florida Panhandle, reported emotions over the war running so high that he worried that his two vessels might be seized. “He directed his survey vessels, the James Hall and the Gerdes, to Passe-a-Loutre at the mouth of the Mississippi River but found the same state of agitation there as in Pensacola. This was in spite of Louisiana not having seceded yet,” according to the official NOAA history “The Coast Survey in the Civil War, 1861-1865.” Gerdes ordered his vessels to New York City. Survey work of the schooner Peirce on Florida’s Indian River and Torrey on St. Joseph’s Bay also were discontinued because of local hostility.
Meanwhile, South Carolina already had seized the Coast Survey vessels Petrel and Fire Fly a few days after its secession. The Confederates went on to burn Fire Fly in Savannah, Ga., in 1864 to prevent its recapture. Petrel, which had been in the care of a Charleston contractor, didn’t survive the war’s first year. A group of Charleston entrepreneurs refit it as a privateer, though with just two guns. In Petrel’s first engagement in summer 1861, the Union Frigate St. Lawrence’s 52 guns made quick work of the Confederate warship, sinking it in the first volley.
One Coast Survey worker, P.H. Donegan, a tide observer at Calcasieu Pass, La., ran into trouble when Customs authorities in Port Aransas, Texas, seized the survey vessel Twilight, which was supposed to pick Donegan up and transport him to safety. Left to fend for himself, Donegan was arrested by the local military commander, who ordered his trial by court-martial for espionage. He was confined to a tiny cell in the parish jail for four months and released in November 1861 through the good offices of the British Consul, according to NOAA’s history.
Also in November 1861, Charles Boutelle, hydrographer to Rear Admirals Samuel DuPont and John Dahlgreen of the South Atlantic Blockading Squadron, which enforced the Union blockade of southern ports, rebuoyed the channel in Port Royal Sound near Beaufort, S.C., while under fire from a Confederate naval squadron. He then personally led five of 16 Union warships down the channel with his own vessel, the Coast Survey steamer Vixen, so the warships could bombard and take forts Beauregard and Walker, according to NOAA’s history.
In February 1863 during the siege of Vicksburg, Miss., another Coast Survey stalwart, Clarence Fendall, reported to his supervisor, “Yesterday, I was three miles beyond our pickets and within 600 yards of the enemy’s batteries. I did not stop work ’til the cannon balls plowed up the ground within 20 feet of us. One of my men had his hat blown off by the wind of a ball, and [another ball] struck the levee just under my plane table. I reckon about all of the inhabitants of Vicksburg were out after me.” Fendall later drew up the map “Approaches to Vicksburg.”
In April 1862, before a naval bombardment of the Confederate Fort Jackson, Coast Surveyors were sent out to survey and establish reference points along the river for indirect artillery fire. Surveyor Harris, who produced the artful sketch of Fort Jackson, reported after one of these forays: “Two of the Confederate gunboats which had been watching me go up the river [in a small boat] when I pulled up the shore … commenced firing at us from a distance of about a mile. My [naval] crew were uneasy and all besought of me to get out, but I told them that they were not going to hit us, that we could see that one shot would fall short of us, another go over us. … I privately looked toward the bank and thought what chance of escape we should have if they attempted to capture us … as I had nothing to identify me as a military man and might be treated as a spy.”
Besides lending tactical support to Union forces, the Coast Survey delivered strategic assistance through a secret Blockade Strategy Board whose chairman was Bache. At the board’s direction, the Coast Survey prepared an eight-part “Notes on the Coast of the United States,” a kind of “Coast Pilot” geared to military strategy with sailing directions for warships, more than 100 maps and charts, and detailed geographic information for the Southeast and Gulf coasts.
The Coast Survey also dipped its toe into national politics during the war, producing an historic 1861 map of the southeastern United States showing in its shadings the distribution of the slave population, based on the 1860 census. “This was a real innovation,” Cloud says. It was the first known use of a map to visually depict social, political and cultural statistical data. Cloud found a long-forgotten 1886 reproduction of the map in a drawer at the National Archives.
He says Edwin Hergesheimer, head of the Coast Survey’s drawing division, ordered the map drawn up. An immigrant who fled Germany after the failed 1848 revolution, Hergesheimer was an ardent abolitionist, according to Cloud. The purpose of the map was to draw a visual link between slavery and secession. Abraham Lincoln reportedly used it to help shape military strategy.
Go to to access the Office of Coast Survey’s Civil War Collection and nearly 400 historical maps and charts.

Alexander Dallas Bache peers through a sextant in the field.
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This article originally appeared in the December 2011 issue.