Category Archives: Petersburg

Mortars and shells wanted at the front: Importance of horizontal fires at Petersburg

We often read the Petersburg siege demonstrated the emergence of “modern war” in some fashion.  The “coffee table book” history draws the the comparison between Virginia trenches of 1864-5 to French trenches of 1915-8.  There is some resemblance, but no more than any functional nature would derive.  Men can only dig a hole in the ground for protection in a finite number of combinations.  Nice surface comparison, but for the most part the trenches are not exactly a mountain of evidence for the “modern war” argument.

If looking to draw positive connections between Petersburg and the tactical nature of warfare in 1915-18, there are two aspects I suggest we examine – the increased use of vertical fires and  changed operational tempo.  That latter point – what we call OPTEMPO in modern parlance – I’ll save for a later post.  But I have mentioned vertical fires earlier this year in relation to the Overland Campaign… particularly Cold Harbor.  And of course, mortars were heavily employed to support the assault after the mine went off.  In the late summer of 1864, the mortars took on added importance at Petersburg. A series of correspondence on August 14, 1864 demonstrates this. That morning, Brigadier-General Henry Hunt wrote to his capable subordinate, Colonel Henry L. Abbot in charge of the siege artillery, directing mortars to the front:

Four 10-inch mortars with a proper supply of ammunition are wanted in the battery near the Taylor house to control a battery of 32-pounder rifles just beyond the crest, distance from 1,200 to 1,500 yards. It would be well to get them out to-day ready to move; they may be ordered into battery to-night. I will inform you then whether to send them. Please answer.

Hunt’s request was to meet a specific tactical need – silencing a Confederate battery that occupied a particularly troublesome position.  The answer to this problem was not direct, or horizontal fire.  Rather he proposed using heavy mortars to fire indirectly, or vertically, onto the Confederate position.  Abbot answered almost immediately that morning and set in motion actions to place the mortars that night. Abbot later suggested a specific position for the mortars, based on earlier experience along that line:

If the 10-inch mortars are ordered forward, I would earnestly request that they be put in the fourteen-gun battery where Pratt’s 4½-inch guns were. The range is essentially the same. The approach to this battery is very good, and to the old battery very bad, a matter of great importance in supplying 10-inch ammunition on account of its great weight; and, moreover, this battery is well made and the old battery very ill constructed, constantly caving under mortar fire.

 Looking back at Hunt’s map illustrating the artillery support during the Battle of the Crater, Pratt’s battery is indicated by the number “24” and circled in blue below:


The correspondence does not specify which Confederate battery was the target.  For the map above, I’ve highlighted one such battery, which would be “beyond the crest” and approximately 1,500 yards distant.  Notice the close proximity to the mine crater. The range cited was well within the capabilities of field pieces. The Confederate guns mentioned were indeed large caliber weapons.  But the Federals might have concentrated the fires of several batteries to damage the battery.  However, having read about the thousands of shells dumped on Fort Sumter, we must ask how long and at what cost would that be completed? 

There is no mention if Hunt required the use of 10-inch case shot from the mortars, as used during the Battle of the Crater.  That particular projectile, of experimental nature, would have done well to silence the Confederate battery while field pieces demolished the earthworks protecting the guns with direct fire. 

Concurrent with the correspondence with Hunt, Abbot also opened a request for more mortar ammunition… and not just a routine request… to Captain Theodore Edson, Ordnance Officer at Fort Monroe:

I am out of my supply of Coehorn mortar shells and the rebels are taking advantage of it. Please send me any shells and wooden plugs which you can possibly procure, on the mail boat, telegraphing me when they start. I don’t care for prepared ammunition. Time is very important.

Backig this up, Abbot further explained the pressing need for mortar ammunition to Brigadier-General George Ramsay, Army Chief of Ordnance in Washington and indicted this was a long standing request:

I have sixteen Coehorn mortars in position and not a shell in depot for them. The rebels keep up a constant mortar fire on us. I don’t care for prepared ammunition; all I want are shells, fuse-plugs, and paper fuses. These must be received very shortly or the army will suffer. I wrote on 15th ultimo, and telegraphed on 19th ultimo and 11th instant for a large supply. Please inform me at once whether I am to be supplied. Please also send 2,000 Parrott time-fuse plugs for siege guns.

The Confederates had also learned the value of vertical fire, and were now in position to employ some of the heavy mortars from Richmond along with some expedient weapons.  And at the same time, the Confederates were commencing production of their own Coehorn mortars.

Fast forward to 1917. When preparing the American Expeditionary Force for combat in France, American officers found themselves short of artillery in general.  But most acutely they called for howitzers and mortars capable of high angle fires.  Henry Abbot would have given them an “I told you!” look.  Vertical fires would become the dominant form of artillery support on the battlefield.

(Citations from OR, Series I, Volume 42, Part II, Serial 88, pages 182-3.)


Artillery support when the Petersburg mine went off

As you might guess, when thinking of the Crater at Petersburg, a subject which crosses my mind is the use of artillery in the operation.  Not to diminish the other aspects of the battle, but the artillery of the Army of the Potomac played an important role there… and is somewhat overlooked in my opinion.  I’m not an expert in the battle.  So I would direct you to one of many folks who have written book length treatments of the battle.

My schedule has prevented me from writing up more on Petersburg up to this time.  Likely, given the sesquicentennial pace, I’ll have to put that on my “after April 2015″ stack.  But I did want to mention the artillery’s role and provide a graphic depiction, by way of Brigadier-General Henry Hunt’s map:


The map, and a busy map it is, includes a table breaking down by battery the type and number of guns engaged on July 30, 1864:


For those who are squinting, the roll call is eighteen 4-½-inch rifles, two 20-pdr Parrotts, fifty-two 3-inch rifles (3-inch Ordnance or 10-pdr Parrotts), thirty-eight 12-pdr Napoleons, ten 10-inch mortars, sixteen 8-inch mortars, and twenty-eight Coehorn mortars.  Grand total is 164 guns and mortars brought to bear on the Confederate lines in support of the assault.

Some of that number were in the 18th Corps sector and not firing directly in support of the assault.  Others were, likewise, firing on the 5th Corps front well to the south of the crater.  But all were firing at some time that morning to suppress or pin down the Confederates in conjunction with the assault.  For comparison, the “great bombardment” by the Confederates on July 3, 1863 during that “contest” at Gettysburg involved about 140 guns.

Hunt’s map indicates not only the battery positions, but also what the targets were.  This adds to the “clutter” on the map. But this is an incredible resource for determining his intent with respect to the fires placed upon the Confederate lines.


The snip above looks at the area of the mine, and just south.  Notice there are more dashed blue lines leading to the Confederate redoubt south of the mine than there are the redoubt above the mine.  Suppression of the Confederate line was the intent there.

Another Federal position worth noting is that of Company C, 1st Connecticut Heavy Artillery.  Battery number 8 on Hunt’s map contained ten 10-inch mortars.  Circled here in blue.


Those mortars fired on approximately 1,000 yards of the Confederate front, to the south of the crater (blue shading in the snip above).  Recall, these mortars were firing, for at least part of the day, case shot as constructed under Colonel Henry Abbot’s instructions.  Battery Number 19, Company B, 1st Connecticut, with six 4-½-inch rifles, located north-east (center-right on the snip above) of the mortars also covered a large section of the Confederate lines.

One problem with these arrangements is that suppressing fire requires a high rate of ammunition expenditure.  Suppressing fire cannot be sustained, even by a master artillery chief such as Hunt, for longer than a few hours.  At some point, fresh ammunition chests must be rotated in.  The assault had to quickly achieve the initial objectives, or lose the suppressing fire support.

510 wagons, 120 guns and mortars, and six days of work: Siege preperations at Petersburg

On July 16, 1864, Brigadier-General Henry Hunt offered a report to the Army of the Potomac’s headquarters in regard to siege preparations.  The report was somewhat inverse of what one might expect.  Rather than focused on what was being done, Hunt responded to an inquiry as to how quickly the siege preparations might be undone (and materials withdrawn) if the Confederates abandon the lines or the Federals opt to abandon the siege for other reasons.  Sort of the staff work that a good commander (in this case Major-General George Meade) presses.  While the conclusions reached by Hunt are of little use to us today, as not supporting “what if” scenarios of interest, the particulars he offered are worth consideration.  They speak to the magnitude of the effort required to lay siege at Petersburg:

In compliance with the direction of the general commanding to furnish a report as to the time which would probably be required to Withdraw the siege train and material in case it should be desirable, I have to state that the siege material which will be brought into requisition if operations are fully entered upon will be: Forty siege guns, for which must be kept on hand in the magazines for daily supply, 6,000 rounds of ammunition; for 6,000 rounds 100 wagons are required; for 30 mantlets 10 wagons; 40 platforms 40 wagons; implements, equipage, &c., 10 wagons; 20 8-inch mortars 20 wagons; 3,000 rounds of ammunition 60 wagons; implements and equipage 20 wagons; 20 10-inch mortars, &c., 100 wagons: 20 Coehorn mortars and ammunition 30 wagons; total, 410 wagons. Twenty more 8-inch mortars are expected for the siege train, and if received will be used. To move them there will be required another 100 wagons.

To move and maintain the siege batteries – 40 guns, 20 10-inch mortars, 40 8-inch mortars (20 on hand at the time, with 20 more expected), and 20 Coehorns – required 510 wagons. With the number of guns, platforms, rounds of ammunition, and wagons in mind, Hunt calculated the time needed to withdraw the siege weapons… in a round about way:

The loading of the material in order to withdraw it must be done by night, and probably even then under fire. The movement of so many wagons can scarcely be made and the noise of loading heavy bodies finished without being heard by the enemy when the lines are so near, as in this case; nor will it do to sacrifice any portion of the material if there is any prospect of its being needed within a month. But little over half the supply of ammunition estimated for has yet been received, although it is sent forward as rapidly as it can be procured. The time needed to load the wagons will be necessarily much longer than ordinarily required at depots. For instance, the positions of the batteries were not selected with any reference to convenience in this respect, and but few wagons can be brought up at a time or placed in favorable positions for loading, so that the number of men who can be employed at any given place will necessarily be limited. At many of the batteries the inconvenience and danger of providing the daily supply of ammunition will make a system of covered ways necessary for the men who transport it from wagons stationed so far in the rear as to find cover from the enemy’s fire, and also from the approach of the wagons to these points. Time, therefore, becomes the most important element; forty-eight hours would, therefore, be necessary, under favorable circumstances, to remove the material.

And did he get to the point?….. Yes.

I do not think it probable that the entire train could be withdrawn in less than three days.

Hunt went on to say the guns and platforms would be moved last, as to at least give the impression the siege was continuing.  With that, Hunt warned, just in case there were any schemes floating about which pointed in directions other than a prolonged siege:

For these reasons the planting of the batteries should not be commenced until it is determined to carry through the siege operations, or, as an alternative, in case a sudden movement of the army should be deemed advisable, we are prepared to sacrifice a large portion of our material.

Meade forwarded this report to Lieutenant-General U.S. Grant, prefaced with a status report of the siege preparations:

In compliance with your wishes, preparations have been continued for commencing the siege. Batteries are being erected for placing guns and mortars in position to silence the enemy’s fire at the salient on the Jerusalem plank road. The chief engineer estimates that it will take eight days to finish these works and have them ready for their armament. The chief of artillery will require three days to unload the vessels now containing the siege guns, mortars, and materials.

Meade added, for emphasis, a summary of Hunt’s conclusions:

In case of withdrawal, besides the three days indicated in his report for withdrawing these guns, if reloaded at the landing where the vessels now are, Broadway Landing, it would require three additional days, but if they are carried to City Point and there reshipped, this last estimate would not enter into the calculation. I have deemed it proper to lay these facts before you, as they may be material to you in your future plans, and to say that I have directed the siege works to go on and in the course of three or four days shall commence the unloading of the guns and material.

Just some figures to have handy… so to speak.  Six days to break-up the siege and move the materials – at great effort.  Sort of means both feet were solidly in the ring by mid-July 1864.

Meade concluded:

The mine will be ready in a day or two, but will not be loaded or sprung till the effect of our operations against the salient is ascertained.

Digging a shaft under the Confederate position was one thing.  Getting all the pieces in place to take advantage of the planned mine blast… well that was another.  More long days of work were required.

(Citations from OR, Series I, Volume 40, Part II, pages 276-7.)