24 March 2013 by Published in: General musings 9 comments

hh9d5Yesterday, I was one of the presenters at the “Gettysburg Before and After” conference put on by Hagerstown Community College. Dennis Frye, the chief historian at the Harpers Ferry National Historical Park, gave a very interesting talk on the role that Harpers Ferry played in the Gettysburg Campaign.

Part of what he discussed caught my attention, as it lends some fascinating new insight into the decisions made by the Army of the Potomac’s high command on July 12, 1863. These insights have caused me to re-evaluate some of those decisions. The facts are worthy of presenting here.

By way of background, the Army of the Potomac’s high command considered throwing a pontoon bridge across the Potomac River at Harpers Ferry because the river was too flooded to ford. Doing so could allow Union troops to get around behind the Army of Northern Virginia’s position. The question was when. Brig. Gen. Gouverneur K. Warren, the army’s chief engineer, had this responsibility. He corresponded with Lt. Col. Ira Spaulding, the chief engineer at Harpers Ferry, who was responsible for the pontoons. The exchange between Warren and Spaulding is worth repeating here.

Here is the first, sent by Warren:

July 10, 1863–10:30 a.m.

Colonel Spaulding, Engineer,
Harpers Ferry:


Events are yet to determine where we shall want the bridge across the Potomac and when. Directions will be sent to you in time. I have ordered the transportation train to join you, and to load up to 200 feet of bridge, which we may require on the Antietam Creek.

By order:

G. K. Warren,
Brigadier General of Volunteers, Chief Engineer

O.R. vol. 27, part 3, p. 628. Spaulding responded the next day.

July 11, 1863–11:45 a.m.

General G. K. Warren:

Lieutenant [Ranald S.] MacKenzie is absent with General Naglee, and I opened your dispatch to him.

The Potomac above the railroad bridge at this point has fallen 4 feet within the past forty-eight hours, and is still falling slowly. It is still 4 to 5 feet above the stage of water which renders it fordable here.

The troops of the Engineer Brigade under my command now here have been constantly at work or making forced marches ever since the army left Falmouth, and I take it for granted they are liable at any moment to be called up for extraordinary exertions. Is it desirable that they should be kept incessantly at work here by General Naglee upon work not indispensable to the efficiency and success of the army?

I. Spaulding,
Lieutenant-Colonel, Volunteer Engineers

O.R. vol. 27, part 3, p. 646. The emphasis is mine. This is a critical piece of intelligence. If the river had fallen 4 feet in 48 hours, and it had only another 4-5 feet to drop in order to be fordable, then at the very latest, the river would be fordable within 48 hours, and probably much less if it continued to be dry. In other words, at that rate of dropping, the Potomac would be fordable no later than July 13. And the Williamsport crossings are upriver from Harpers Ferry, meaning that they would fordable before the crossings at Harpers Ferry.

On July 13, as the Army of Northern Virginia was preparing to cross that night, Warren wrote:

July 13, 1863–5 p.m.

Colonel Spaulding:

We may want a bridge across the river before long. If sending away the 100 men to repair the canal will not interfere with laying the bridge, it is desirable to have it done.

G. K. Warren,
Brig. Gen. of Vols., Chief Engineer, Army of the Potomac

O.R. vol. 27, part 3, p. 672. The pontoon bridge was laid the next day, AFTER the Army of Northern Virginia had already made it to safety across the Potomac. Brig. Gen. David M. Gregg’s Second Cavalry Division had a major engagement with Confederate cavalry at Sandy Hook, near Harpers Ferry, the next day.

There’s some real food for thought here. Specifically, on July 11, Spaulding advised Warren–the Army of the Potomac’s chief engineer–that the Potomac River was dropping and would be fordable no later than July 13, assuming no more rain fell. Once the Potomac could be forded at Williamsport, which is 15 or so miles upstream from Harpers Ferry, the Army of Northern Virginia could cross to safety. This means that Lee could escape unless the Army of the Potomac moved quickly to attack it.

On the night of July 12, Maj. Gen. George G. Meade, commander of the Army of the Potomac, held a council of war with his officers. Meade was anxious about whether to attack the Army of Northern Virginia’s entrenched positions along the Potomac, the strength of which was obvious to anyone caring to look. Meade, his chief of staff, Gen. Andrew A. Humphreys, and his corps commanders all attended. They included: Gens. James Wadsworth (filling in for an ill Gen. John Newton, temporary commander of the 1st Corps), William Hays (in temporary command of the Second Corps), William H. French (commanding the 3rd Corps after Maj. Gen. Daniel E. Sickles was severely wounded at Gettysburg), George Sykes (5th Corps), John Sedgwick (6th Corps), O. O. Howard (11th Corps), Henry W. Slocum (12th Corps), and Alfred Pleasonton (Cavalry Corps). Also attending were Gen. William F. “Baldy” Smith, who commanded a division of emergency militia troops that had joined the Army of the Potomac, and chief engineer Warren.

Meade strongly favored an attack on July 13, but he wanted the support of his corps commanders before issuing the orders to do so. Wadsworth, Howard, and Pleasonton favored an attack. So did Warren. Sedgwick, Slocum, Sykes, French, and Hays opposed it. However, none of Humphreys, Pleasonton, or Warren were permitted to vote, meaning that a majority of the commanders with a vote opposed the attack. While Meade could have overridden the vote and could have ordered the attack anyway, he reluctantly took the advice of his commanders, which was to spend the 13th probing the Confederate lines and to attack on the 14th. Nobody knew that Lee’s army would steal away on the night of the 13th and that the general advance of the Army of the Potomac on the morning of the 14th would find the trenches empty and the Confederates gone.

The record fails to indicate whether Warren advised the council of war of the critical intelligence forwarded by Colonel Spaulding–that the Potomac was steadily dropping and would be fordable the next day if the rains continued to hold off. Warren was a conscientious officer, and presumably he did pass on that important piece of information. But we do not know for sure. Had he failed to do so, one cannot help but wonder whether that critical piece of information might have changed the outcome of the July 12 council of war.

Conversely, if Warren did, indeed, pass along that critical intelligence, that makes the vote of the five corps commanders who opposed an attack all the more puzzling. And it also makes Meade’s decision not to override their vote and order the attack anyway all the more perplexing. It is a cliche that councils of war never vote to fight, so the outcome of the July 12 council was somewhat predictable. Another cliche comes to mind: for want of a nail, a kingdom was lost.

In the end, I remain convinced that short of ordering the attack on July 13–an attack that had no guarantee of success, given the incredibly strong position held by the Confederates–there is little, if anything, that Meade could have done to prevent the Army of Northern Virginia from making its escape once the depth of the Potomac River dropped enough for it to become fordable. And, in the end, I cannot fault Meade for not wanting to attack that incredibly strong position–bristling with artillery behind earthworks–without having a better idea of its make-up and without having some idea if there were any weak spots to exploit or particularly strong points to avoid. A good army commander would not make such decisions rashly, and Meade was not a rash man. It’s entirely possible, then, that this critical piece of intelligence might have made no difference whatsoever in the big scheme of things. But it is tantalizing.

This is an incredibly fascinating twist, and it demonstrates how the smallest scrap of information can have far-reaching and unforeseen consequences. Thanks to Dennis Frye for passing this information along.

Scridb filter


  1. Richard K. MacDonald, Jr.
    Sun 24th Mar 2013 at 8:20 pm

    I love the Harper’s Ferry area, this was cool too my friend.

  2. Sun 24th Mar 2013 at 8:37 pm

    Good work Eric.. just goes to show human nature and the weather can never be discounted as a factor in any human endeavor..

  3. Chuck
    Mon 25th Mar 2013 at 7:00 am

    Eric: Interesting… thanks for posting. Was there no other source of info on flood levels available to Meade?

  4. J David Petruzzi
    Mon 25th Mar 2013 at 11:57 am

    Very neat discovery – and I missed it and never considered it either. I’m inclined to believe that Warren (being the thorough and meticulous engineer that he was) indeed brought this up either at the meeting or to Meade personally. It should have gotten them all thinking that Lee could escape by the night of the 13th. I wish we’d caught these missives to include in our “One Continuous Fight.” It would have mandated we include this discussion…

  5. Mon 25th Mar 2013 at 1:44 pm

    Absolutely right, JD.

  6. John Foskett
    Mon 25th Mar 2013 at 2:39 pm


    That’s an extremely nice piece of detective work.

    My great-great Uncle Isaac was in Co. D, US Engineers Battalion, and on July 12 they were on the march to Sandy Hook. His diary indicates that July 13 was “rainy” while they “lay in camp” near Sharpsburg, so the “river falling” window may have started closing by very late that day (although he records July 14 as “pleasant”). As an aside, he reached Sandy Hook on July 15 “with a lot of rain”. They were detailed on arrival to repair the “Ware”[?] Bridge over the river on that date.

  7. Fri 29th Mar 2013 at 9:10 am

    There’s a lot I could offer as speculation here. As I’ve mentioned to Eric in emails, there are several other bits if information that must be taken in context with these two messages. First off, a significant portion of the army’s bridging equipment was in DC being repaired (remember in June 1863 those engineers put up numerous bridges to include the major crossing at Edwards Ferry). So we must ask if the AOP had enough equipment in position to support any crossing at that particular moment in time.

    Secondly, the means to move that equipment was degraded somewhat. The engineers had animals to transport, but those were scattered out due to mission requirements. The BEST way to move bridging equipment on the Potomac was, as done in the last weeks of June 1863, by way of the C&O canal. BUT some fellow by the name of Stuart had sufficiently broken that transportation link when he made that “glory” ride to Gettysburg (ahem… one more “consequence” of Stuart’s ride if you ask me).

    Third, during the late June bridging operations at Edwards Ferry, the engineers spoke of their preferences for locations to bridge the Potomac. Harpers Ferry was not one of them, and the justification was the narrow (non-existent) flood plain. Further down river, the Potomac enters more open country, particularly around Berlin and again around Leesburg. The engineers preferred those locations as they were less affected by the rise and fall of the river (ask me about the mechanics of the bridging and I’ll write you a book). HOWEVER, I have not seen any discussions of the pursuit crossings and can only offer the preferences of June in lieu.

    Lastly, I’d also point out that Warren was not as involved with the tactical decisions with respect to the engineer brigade as we might think. While he provided suggestions for the June 1863 crossing of the Potomac, he was only distantly involved with the operation. Of course the brigade commander (Benham) was likewise less involved than he should have been. The task fell to lower grade officers – Spaulding, Turnbull, Spears,…. So any bridging done on July 12-14 would have fallen to those guys again. Thus, until I see direct correspondence involving those officers that provides details, I’m not convinced any bridging operation was seriously considered.

    Lastly, let’s look at the chess board here. If Meade were to throw part or all of the AOP over at Harpers Ferry, what does he gain? Now the AOP has the Shenandoah (a formidable barrier in its own right) at their back. On the other hand, if the AOP moves quickly into Loudoun Valley (even after Lee’s recrossing), isn’t that a more advantageous position? Not only does the AOP stay between the ANV and Washington, but also is in position to interdict movement into Culpeper and thence back to the Rappahannock lines.

    Thanks, Eric. Now I have yet another line of research for my studies!

  8. John Foskett
    Fri 29th Mar 2013 at 10:39 am

    Craig: This is extremely interesting to me. In his discussion about laying the bridges at Edwards Ferry on June 20-21, Isaac mentions building a bridge across “Goose Creek” on June 23. Any idea where that is and what was going on?

  9. Sat 30th Mar 2013 at 6:57 am

    John, yes. On June 22, AOP HQ called for a bridge over Goose Creek at its mouth. So by June 23, that bridge went in. The bridge was placed to facilitate movement of supplies. (The first bridge at Edwards Ferry was across the Potomac, placed on June 20-21, to supply the 12th Corps. I would much like to hear what your g.g.Uncle wrote in his diary for the last half of June. I’ve studied the crossing at Edwards Ferry extensively, managed to get a marker at the location, and have posted as much information as I can here: http://markerhunter.wordpress.com/edwards-ferry-crossing/


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