The Civil War Day by Day

Suppressing the rebellion required conquest of vast territory and has never before been mapped day by day and unit by unit. The rebel states covered some 780,000 square miles, more than Britain, France, Spain, Germany, the Low Countries, and Italy combined. Sherman’s 1864 drive on Atlanta hung, as he later wrote, on a “single stem of railroad, four hundred and seventy-three miles long.” This map follows the advance of federal arms over four years of war.

The Civil War Day by Day is a project by Jeremy Neufeld. Follow @LiveCivilWar on X to follow the war one day at a time.

How this map was made

The map reconstructs the daily positions of 3,220 federal regiments, batteries, and companies from their regimental histories. Those histories record battles, marches, transfers, and stretches of garrison duty, but rarely give a continuous account of a unit’s movements. The map fills the gaps using the rules described below. I am actively working on adding in rebel units.

Source. The unit histories come from Part III of Frederick H. Dyer’s A Compendium of the War of the Rebellion (Des Moines, 1908).

Extracting events. A Claude model converted each history into dated events. Dyer generally gives the year only when it changes, so the model had to carry it forward. Entries such as “Duty at Helena till April, 1863” were treated as intervals beginning at the previous event. Brigade assignments, officers, and casualty totals were excluded when they supplied no location.

Checking dates. Missing a change of year can misdate an entire sequence of events. To detect these errors, I compared dates across units that recorded the same battle. A battle qualified as a date anchor if at least 85 percent of the units placed it in the same calendar month and year; 930 qualified. Where a unit dated an anchor at least a year incorrectly, the surrounding sequence was shifted to match, stopping where chronological order resumed.

Locating events. The histories contain 26,303 distinct event phrases. A Claude model assigned each a representative point using the phrase, neighboring entries, Civil War geography, and web searches for obscure places.

A second model independently located 5,580 phrases: all those used at least three times, plus those used twice that received a low-confidence rating in the first pass. These phrases cover 75 percent of dated entries. A third pass reviewed the 241 cases where the two locations differed by more than 30 km, considering every unit’s use of the phrase.

Identical names sometimes refer to different places. “Franklin,” for example, refers to West Virginia in 1862, Tennessee in 1863 and late 1864, and Louisiana in mid-1864. Recurring names of this kind were divided by date into 2,333 episodes and located separately.

I also reviewed entries that implied unusually large jumps: more than 300 km from both neighboring entries, or more than 400 km from the preceding entry within ten days without a transport route. This led to 534 location corrections. The remaining jumps were retained, chiefly for raids, detached companies, and trips home.

For campaigns, the map uses the next recorded location as a destination when one is available nearby in time. “March to the sea, November 15 to December 10,” followed by “Siege of Savannah,” moves the unit from Atlanta to Savannah over the campaign dates. Without a nearby subsequent entry, the campaign is represented by a single point. I am actively working on more detailed routes of march.

Movement. Unless an entry describes movement, a unit remains at its last recorded location.

The map treats “Moved to,” “Ordered to,” and “Movement to” as rail or water transfers. These follow a dated network of Union-held railroads, rivers, and sea lanes. For example, the Mississippi below Memphis becomes available after the fall of Vicksburg, and City Point serves as the James River base from June 1864. “March to” entries follow straight lines.

Rail routes were matched to Jeremy Atack’s historical railroad data by shortest-path search, using track in operation by 1861 where available and later track where necessary. The network includes train-ferry crossings. Each match was then reviewed against the historical route.

Four network links remain straight because the data contain no usable track:

• Johnsonville–Nashville: the Nashville and Northwestern, completed by the army to the Tennessee River in 1864, is missing west of Kingston Springs.
• Grand Rapids–Kalamazoo: the railroad did not open until 1870.
• Plattsburgh–Troy: the wartime connection included a lake steamer.
• Annapolis Junction–Odenton: the western leg of the Annapolis and Elk Ridge is missing.

Named stops are preserved in sequence, with a separate transport mode for each leg. Thus “Ordered to Hilton Head, S.C.; thence to Gloucester Point, Va.” produces two successive destinations.

Transfers recorded with a single date are assigned roughly one day per 250 km of route; single-date marches are assigned about 25 km per day. Where an entry indicates transport but the network has no Union-held route, chiefly in Texas and the far West, the unit stays at its departure point until appearing at its destination on arrival.

After a battle, expedition, or campaign lasting no more than ten days, a unit returns to its previous camp, duty post, or siege line if that location is within 50 km and was occupied within the preceding 45 days. It remains there until the next entry. After longer campaigns, it stays at the campaign’s representative point.

A unit ordered home returns to where it was organized. Units disappear the day after their final muster-out, or 45 days after their last dated entry where no muster-out date can be placed.

Detachments. When Dyer records part of a unit operating separately, the map gives it a separate marker, labeled by company or as a detachment. This includes cases such as the 3rd Maryland’s “old members” serving in the Atlanta campaign while the rest of the regiment was in Virginia.

A detachment appears separately only when the rest of its regiment is recorded more than 40 km away. Companies serving with their regiment remain in its marker. Detached elements are not counted twice.

A detachment leaves the regiment shortly before its first recorded date. A couple of days after its last entry, it begins returning to the regiment’s current position and merges with it. If the regiment is more than 150 km away, departure and return occur without an animated journey. The map includes 1,101 such outings from 448 units.

Armies, corps, divisions, and brigades. Each regiment’s brigade, division, corps, and army come from its own history, which gives them by month. In a month when a unit changed assignment, the old one holds through the 15th. Selecting a place lists its units by army, corps, division, and brigade, and each formation opens a card showing where its units are that day, its subordinate formations, and its commander.

Commanders come from Part I of the Compendium, “Number and Organization of the Armies of the United States” (printed pages 9–578), which lists each army, corps, division, and brigade with its commanders and their dates. Part I was also transcribed from the page images and read a second time in full. Where Part I and a regiment’s history place the unit differently, the map follows the history. Names appear in their standard spelling, for generals the form of the article title in Wikipedia’s lists of Union generals, and a log records every change from Dyer’s printed form.

Symbols. Each marker represents the units at a location. Its NATO-style symbol shows the most common arm of service there: crossed diagonals for infantry, a single diagonal for cavalry, a dot for artillery, a bridge symbol for engineers, or an empty frame for other units. All Union units are blue.

Marker size increases logarithmically with the number of units; the legend shows 1, 10, 100, and 300. Counts appear beneath markers as you zoom in, and hovering lists the units. Selecting “Dots” under Layers replaces military symbols with circles, with counts inside where space permits.

Counts in the side panel are by place: a unit counts where its history puts it on that day. At wide zooms a marker can combine several nearby places, and the panel says when it does.

Corps badges. Corps badges are redrawn from period depictions: the patterns printed with Joseph Hooker’s circular of March 21, 1863, the color plates in John D. Billings’s Hardtack and Coffee (1887), and the Quartermaster General’s Flags of the Army of the United States (1887). On the map they appear in blue. On cards they take the division’s color where it is documented, and red, white, and blue for the first three divisions where it is not.

Crossed sabers identify locations where units are recorded in a battle, action, skirmish, or siege on the selected date.

State and territory boundaries. Boundaries follow the Newberry Library’s Atlas of Historical County Boundaries and change with the date. Kansas becomes a state on January 29, 1861; West Virginia on June 20, 1863; and Nevada on October 31, 1864. Territories are hatched.

Political status. State colors show political status, not military control. Each transition is tied to a dated event identified by one researcher and checked against a second, independent source.

The eleven seceded states take the warmer tint when their conventions adopted secession. Tennessee’s date is May 6, 1861, when its legislature acted. These dates precede some popular referendums and admissions to the Confederacy.

Stripes indicate competing state governments recognized by the opposing sides:

• Virginia: July 13, 1861, when the U.S. Senate seated senators from the Restored Government at Wheeling.
• Missouri and Kentucky: November 28 and December 10, 1861, respectively, when they were admitted to the Confederacy while their Union governments remained in office.
• Louisiana and Arkansas: March 4 and April 18, 1864, when Union governors Michael Hahn and Isaac Murphy were inaugurated.

Military governorships, including Andrew Johnson’s in Tennessee, do not count as separate state governments.

States take a pale tint when their Confederate governments end: under U.S. authority, but not yet readmitted to Congress. These transitions fall between May 1 and June 17, 1865, generally when Confederate governors were arrested, resigned, or fled. Virginia uses President Johnson’s executive order of May 9, 1865. Tennessee, whose Confederate legislature last met in March 1862, changes on April 5, 1865, with William G. Brownlow’s inauguration.

Two dates are conventions because no precise date is documented: June 2, 1865, the surrender of the Trans-Mississippi Department, for the end of Missouri’s Confederate government in exile; and April 9, 1865, for Kentucky’s.

Congressional readmission falls outside the map’s period: Tennessee on July 24, 1866, and the remaining states in 1868–70.

Union slave states and the District of Columbia are tan until slavery was abolished locally: April 16, 1862, in the District; November 1, 1864, in Maryland; January 11, 1865, in Missouri; and February 3, 1865, in West Virginia. Kentucky and Delaware remain tan until ratification of the Thirteenth Amendment was completed on December 6, 1865. Seward certified ratification on December 18.

Other countries. Countries outside the United States are gray, with names and rulers appropriate to 1861–66. Labels include British North America, before Confederation in 1867; Russian America, before its sale to the United States that year; and Spanish Cuba and Puerto Rico. Santo Domingo appears under Spanish rule from March 1861 to July 1865, then as the Dominican Republic.

Mexico is labeled as the republic of Benito Juárez, which the United States recognized. From July 10, 1863, when an assembly convened under French occupation voted for a monarchy, a second line identifies the French-backed empire of Maximilian.

International boundaries use Natural Earth’s modern lines as approximations. Lines are solid where a treaty had already fixed the boundary, as between British Honduras and Guatemala in 1859. They are dashed where settlement came later: Mexico–Guatemala in 1882, Mexico–British Honduras in 1893, the Alaska panhandle in 1903, boundaries among the Central American republics in 1906–92, and Haiti–Dominican Republic in 1929. Internal boundaries in British North America are omitted.

Railroads. The railroad layer uses Jeremy Atack’s historical GIS database. It shows 29,700 miles by 1861, based on G. R. Taylor and I. D. Neu’s maps of that year’s network, and another 3,070 miles first recorded in the next benchmark: J. T. Lloyd’s map of railroads “finished to June 1863.”

Those additional lines appear on June 30, 1863, although some opened earlier. A few short segments dated 1862 or 1865 in Atack’s data appear at the start of those years. This layer shows the existence of track, without accounting for military control, destruction, or repairs.

Cities. The city layer contains the 100 largest urban places in the 1860 census, located using U.S. Geological Survey GNIS coordinates. Few were in the South: Atlanta, population 9,554, ranked 99th. Smaller cities in the set appear as you zoom in and space permits.

Timeline. The shaded area shows the number of units Dyer records in a battle, action, or siege each week.

The 18 highlighted events were selected manually, starting with the Civil War Sites Advisory Commission’s Class A battles whose English Wikipedia articles received the most views in 2021–25. Sixteen are among the 45 battles the Commission classified as having “a decisive influence on a campaign and a direct impact on the course of the war” in its 1993 Report on the Nation’s Civil War Battlefields. The other two are the Battle of Atlanta, July 22, 1864, rated Class B, and Sherman’s March to the Sea.

The March follows Dyer’s dates, from “March to the sea” beginning November 15 through the “Siege of Savannah” ending December 21, 1864. The March and the siege of Vicksburg each span more than a month and appear as thin lines below the event row.

Battle dates and casualty estimates come from National Park Service summaries compiled in Jeffrey B. Arnold’s acw_battle_data, checked against the archived summaries. Names follow Union usage, such as Bull Run and Spotsylvania, where the Commission uses a different name.

Each event mark spans its dates and displays its name on hover. Clicking moves the map to the first day and selects the engagement at the location derived from Dyer’s entries. Fort Sumter is placed manually; the March centers the map on Georgia.

Limitations. The map counts units, not soldiers. A battery of 100 men and a regiment of 800 each count as one.

Locations vary in precision. A campaign may be represented by one point, a long “duty at” entry holds a unit in place, and gaps between entries generally leave it at its last recorded location. The movement and return rules above approximate some of these gaps; they do not reconstruct daily itineraries.

Dyer often omits short movements. Most histories, for example, go directly from Franklin on November 30, 1864, to Nashville on December 15–16 without recording the retreat. Units can therefore remain on a battlefield longer than they actually did.

Transcription errors remain possible, and a small number of characters are illegible in both copies. A small number of histories, chiefly militia and Veteran Reserve Corps units, are too fragmentary to date.

Sources.

• Frederick H. Dyer, A Compendium of the War of the Rebellion (1908), Parts I and III; Emory University copy (Internet Archive) and University of Michigan copy (HathiTrust).
• William F. Fox, Regimental Losses in the American Civil War, 1861–1865 (Albany: Albany Publishing Company, 1889); University of California copy (HathiTrust).
• John H. Long, ed., Atlas of Historical County Boundaries, Newberry Library; state-level boundaries accessed through USAboundaries.
• Natural Earth: rivers, lakes, and country outlines.
• National Atlas of the United States, “Streams and Waterbodies of the United States” (U.S. Geological Survey, December 2005), 1:2,000,000: the James River in Virginia and the tidal rivers, bays, and sounds that the 1860 state outlines draw as land.
• Jeremy Atack, “Historical Geographic Information Systems (GIS) database of U.S. Railroads for 1830–1865” (May 2016; revised October 31, 2023).
• Campbell Gibson, “Population of the 100 Largest Cities and Other Urban Places in the United States: 1790 to 1990,” Population Division Working Paper 27, U.S. Census Bureau (1998), table 9.
• U.S. Geological Survey, Geographic Names Information System.
• Civil War Sites Advisory Commission, Report on the Nation’s Civil War Battlefields (National Park Service, 1993).
• National Park Service battle summaries, compiled in Jeffrey B. Arnold’s acw_battle_data.
• John D. Billings, Hardtack and Coffee; or, The Unwritten Story of Army Life (Boston: G. M. Smith, 1887), ch. 13, “Corps and Corps Badges.”
• Quartermaster General, Flags of the Army of the United States Carried during the War of the Rebellion, 1861–1865 (Philadelphia, 1887).
• The War of the Rebellion: A Compilation of the Official Records of the Union and Confederate Armies, ser. 1, vol. 25, pt. 2, p. 152 (Hooker’s circular on corps badges).
• Wikipedia, “List of American Civil War generals (Union)” and “List of American Civil War brevet generals,” for standard spellings of generals’ names.