War is a collaborative effort, and collaboration requires communication. The means, method, mode, and reliability of an army’s communications network often directly impacts on that army’s performance at tactical, operational, and strategic levels. What confounds me is how so many historians overlook analysis of the communications networks when discussing, not just Civil War operations, but ANY military operation. So, with a bit of “practice what I preach” in mind, let me look at the communications network that supported the Army of the Potomac during the Edwards Ferry crossing.
The Signal Corps detachment supporting the Army of the Potomac provided some rather detailed reports of the Gettysburg Campaign, and thankfully those are preserved in the Official Records. In addition, the Chief of Signal for the Army, Captain Lemuel B. Norton, provided a detailed map indicating the locations of signal stations used during the campaign. The best digital copy of the map I’ve found is included with the David Rumsey Collection, as part of a collection from The Atlas to Accompany the Official Records. Here’s a cut from that plate, focused on the area of operations from June 15-28:
Specific to the activities around Edwards Ferry, the closer crop below annotates the specific stations in use at the time of the crossing:
I’ve placed red flag icons (as red stands out on the map better) at stations indicated on the map. Dashed red lines indicate signal flag communication links. Solid red lines indicate telegraph connections. Of note, I’ve only highlighted those stations and links indicated on Norton’s original map. There are other links that will be noted below. Also as this map covers the entire campaign (through August), several stations indicated on the map, particularly in Loudoun Valley, were not active at the time of the crossing.
In his official report, Norton provided a chronological summary of events. [Note 1] The report notes a use of both signal flag stations and telegraph to support an army on the move.
As Maj. Gen. Joseph Hooker’s headquarters entered the Washington defensive perimeter, the signal officers linked into the telegraph network along the rail lines. The first connection noted was at Fairfax Station on June 16. As the Army’s headquarters moved near Fairfax Court House, on June 18, not only were connections established back to Washington, but also out to Herndon Station on the Alexandria, Loudoun, & Hampshire where General John F. Reynolds was then located. The following day that line was extended further to Guilford Station (noted in the I Corps movement details). (During this time, Captain B.F. Fisher, the Army’s Signal Officer, was captured near Aldie, and Norton assumed the role of Chief Signal Officer for the command.)
Where the signal personnel could not use telegraph, signal flag stations were required. On June 20, two signal officers were assigned to each corps for this purpose. This extended network of wig-wags included stations at the high ground northeast of Guilford Station, Trappe Rock (XI Corps), and Leesburg (XII Corps). Not mentioned on the report but noted on the map was a station at Gum Spring for the III Corps. On the 21st and 22nd additional stations extended the links outward to the II Corps sector on the Bull Run Mountains. And on the 23rd an additional station at Aldie brought the V and Cavalry Corps into the network. Such only excluded the VI Corps which was stationed near Army headquarters at the time.
These signal stations also interfaced with the larger flag station network. The station at Leesburg (and presumably that at Guilford Station also) had line of sight to the station in Poolesville, Maryland. From there signals passed to the Sugarloaf Mountain station, which connected to a station at Point of Rocks further on to Maryland Heights. Thus the “net” extended far enough to include those actually watching the Army of Northern Virginia cross the Potomac.
Thus a revised map of the signal network supporting the army looked thus:
Note that Norton’s original map contained some inaccuracies. First, the I Corps headquarters is depicted beyond Broad Run, and it was instead east of that creek. Second, Howard’s XI Corps headquarters was likely near the railroad bridge over Goose Creek, and further north than indicated by Norton. Norton noted the signal station at Gum Spring for the V and Cavalry Corps, when it was instead used by III Corps at that time. The map overlay above adds stations for II Corps at Thoroughfare Gap in the Haymarket area and one in the Aldie area. The overlay also adds solid lines indicating the telegraph lines used on both sides of the Potomac.
The single point of failure, from the perspective of internal communications, was the station at Guilford Station. Through that station, all orders outbound to subordinate corps were routed. Furthermore much of the inbound reports and intelligence arrived through that station. Granted, the transfer from that point was on the telegraph, but still one more hop before arriving at the consumer. Even past that bottleneck, links to II, V, and the Cavalry Corps required relays. The network was thus prone to breaks. Such was noted by Reynolds on June 25 as the army began moving. [Note 2]
Given the telegraph network topology, messages from Maryland Heights could be forwarded from Point of Rocks onward to Washington faster than they were forwarded to Hooker at Fairfax. Many of the dispatches forwarded over June 23-26 have notes indicating the time received at the War Department. [Note 3] Generally redundant communication paths are good for command and control. But in this case, such lead to a situation where the higher headquarters was perhaps privy to much more than the commander in the field, with regard to the tactical situation.
And of course with these extended communication lines, the inevitable miss-communications occurred. On June 24, a message forwarded from Maryland Heights at 11 a.m. stated Confederate artillery and wagons were passing through “Charlotte.” At 1:10 p.m. Hooker queried Maj. Gen. Slocum at Leesburg as to the reported location, insisting “Charlestown” must be implied. Later Slocum provided a correction. The flow of this dispatch was notable – from Captain Daniels at Maryland Heights, through Col. Albert Myer (Army Chief of Signal) at Poolesville, thence presumably through Leesburg and Guilford Station before reaching Hooker. With the time stamps of the messages, this implied a two hour delay relaying the note. [Note 4]
As the Army started movement on June 25, the Signal Officers folded up this network and proceeded with the command across the Potomac. Reports from the commands indicate a telegraph station remained at Poolesville, from which a link to Washington was maintained. As Army headquarters continued to Frederick on the 27th, the Signal Officers attempted to use Sugarloaf Mountain as a relay point. This effort failed due to what Norton recorded as “the unfavorable condition of the atmosphere.” After the 27th, services of the Signals was not needed again until June 30. By that time, the Signal Officers were busy establishing stations ranging from Taneytown to Emmitsburg, and then north to Gettysburg. [Note 5]
In hindsight, the network supporting the Army from June 23-27 was a patchwork affair to say the least, but it functioned. The delays and loops in the system certainly added to the fog of war that clouded Hooker’s view of the situation. No doubt had Hooker displaced the headquarters at least to Guilford Station, some of these issues could have been eased if not mitigated. I would not go as far to say the communications network caused the friction between Hooker and Washington, or between Hooker and key subordinates. But the network, as it function at that time, certainly did nothing to ease the friction.
- Report of Capt. Lemuel B. Norton, Chief Signal Officer (No. 17), Army of the Potomac, September 18, 1863. OR, Series I, Volume 27, Serial 43, p. 199-207. Most of the narrative for this section of the post is derived from Norton’s report unless otherwise noted.
- Dispatch from Reynolds to A.A.G. Seth Williams, June 25, 1863. OR, Series I, Volume 27, Serial 45, p. 316. Reynolds noted that orders bound for Meade and Pleasoton were not transmitted as the XI Corps relay station was taken down.
- A good example is found in a dispatch from Brig. Gen. Daniel Tyler, Maryland Heights to Hooker, June 23, 1863. OR, Series I, Volume 27, Serial 45, p. 275. The dispatch reports the movement of Confederates beyond Sharpsburg with another column moving up from Charlestown. A time stamp indicates a copy was received by the War Department at 9:15 a.m. that morning. Thus the War Department was not receiving dispatches forwarded by Hooker, but the dispatch itself being relayed through the system. Compare this to a dispatch from Gen. Slocum relaying signal traffic to Hooker at 10 p.m. the same day (Serial 45, p. 272), which was a follow up to the original, and did not pass through the War Department before reaching Hooker.
- The entire sequence is recorded on OR, Series I, Volume 27, Serial 45, p. 284.
- Beyond the scope of this article, the performance of the Signal Corps at Gettysburg is well covered by other sources. For battlefield visitors, I would suggest the tour outlined at the Civil War Signal Association site’s tour of the battlefield.