Civil War Field Fortification

Report of Brigadier General John G. Barnard, Chief Engineer, Army of the Potomac, of Operations During the Siege of Yorktown, April and May, 1862.

From

The War of the Rebellion: A Compilation of the Official Records of the Union and Confederate Armies.

Series I, Volume XI, Part I, Pages 316 -- 321.

Note:

This report is offered here as an example of an operational report written by an exacting professional military engineer.  Errors in the original document have been reproduced in this transcription.

Camp Near Yorktown, Va., May 6, 1862. 

  Sir: The accompanying drawing (map No. 2) gives with accuracy the outline and armament of the fortifications of Yorktown proper, with detached works immediately connected therewith (map No. 3). The general outline is almost the same as that of the British works in the Revolution. The three bastioned forts looking toward our approaches appear to have been earliest built, and have about 15 feet thickness of parapet and 8 to 10 depth of ditch, the width varying much, but never being less at the tops of counterscarp than 15 feet, and I should think generally much more. The works extending around the town from the western salient of fronts just mentioned appear to have been finished during the past winter and spring. They have formidable profiles, 18 feet thickness of parapet, and generally 10 feet depth of ditch.

     The water batteries had generally 18 feet parapet, the guns en barbette. They were (as well as all the works mentioned) carefully constructed, with well-made sod revetments. There were numerous traverses between the guns and ample magazines, how sufficient in bomb-proof qualities I am unable to say. The water batteries were as follows: No. 1, five 8-inch columbiads; No. 2, four 8-inch columbiads; No. 3, three 32sand one 32 navy; No. 4, three 32s (1827); No. 5, two 32s; No. 6, three 9-inch Dahlgrens and one 10-inch Dalhgren; No. 7, on beach, three 8-inch columbiads and one 64-pounder, besides a 42-pounder carronade, intended to sweep the shore.

     The first two guns of the works on the heights bore upon the water as well as the land, and were of heavy caliber. The guns in position on the fronts of attack (the first two of which bore on the water) were as follows, commencing on the left. (See the list herewith, which gives all the guns in position or for which there were emplacements.) The emplacements were all occupied before the evacuation by siege guns, rifled, 4 1/2-inch 24-pounders and 18-pounders.

     In Fort Magruder (the first exterior work) there were found one 8-inch columbiad, one 42-pounder, and one 8-inch siege howitzer, the two former en barbette.  The sketch will show the emplacements for guns on field or siege carriages, making, I think, with the foregoing, twenty-two. Two of these were placed behind traverses, with embrasures covered by blindings. The two external redoubts with the connecting parapets formed a re-entrant with the fronts of attack, and all the guns bore on our approaches. It will be seen, therefore, that our approaches were swept by the fire of at least forty-nine guns, nearly all of which were heavy, and many of them the most formidable guns known; besides that, two-thirds of the guns of the water batteries and all the guns of Gloucestor bore on our right batteries, though under disadvantageous circumstances. Besides the above there were emplacements for four or five guns in the entrenchments running from Yorktown toward Fort Magruder. The guns on barbette carriages had not any protection, except in a few cases sand bags had been piled up. It is supposed that they awaited further indications as to the localities of our batteries before constructing merlons. For the guns on ship or siege carriages some arrangements had been made for protection by building up sodded merlons, or by sand bags and cotton bales, but as they were they would have been very inefficient against our fire.

     The ravine behind which the left of the Yorktown fronts of attack was placed was not very difficult, and its head formed depressions in front of their left imperfectly seen by their fires, and form which access could be had to the ditches, but we could not be sure of this fact before the evacuation. The enemy held, by means of a slight breastwork and rifle trenches, a position in advance of the heads of these ravines as far forward as the burnt house. Our own rifle trenches were advanced to within 60 yards of the burned house -- a point from which the day before the evacuation I made my last reconnaissance. Owing, however, to the fact that the enemy's riflemen were better concealed by shrubbery, &c., than our own, who had just constructed their trench the night before, did not dare to show their heads or use their rifles, and I was unable to examine the grounds in front.

     The ravines which head between the Yorktown fortifications and exterior works are deep and intricate. They were tolerably well seen, however, by the works which run westwardly from the Yorktown works, and which were too numerous and complicated to be traced on paper.

     Fort Magruder, the first lunette on our left, appears to have been built at an early period, probably before the rear of Yorktown was inclosed, and to prevent the approach of an enemy who should attempt to pass the ravines. It had a moderately strong profile, but its gorge, a mere stockade, was taken in reverse by our Battery No. 13.

     The Red Redoubt (square) farther to the left answered very well as a means of continuing the line and securing against assault by ordinary means, but its front was almost wholly occupied by barbettes for field or siege guns, and its interior was seen from our Battery No. 13. The exterior connection between this work was first a rifle trench, probably afterwards enlarged into a parapet, with external ditch and an emplacement for four guns in or near the small redan in center.

     Behind this they had constructed numerous epaulments, with connecting boyaux, not fully arranged for infantry fires, and mainly intended, probably, to protect their camps and reserves against the destructive effects of our artillery. From the Red Redoubt these trenches and epaulments ran to the woods and rivulet which forms a head with the Warwick, and continue almost without break to connect with the works at Wynn's Mill. This stream mentioned (whatever be its name, the term 'Warwick,' according to some, applying only to the tidal channel from the James River up as high as Lee's Mill) is inundated by a number of dams from near where its head is crossed by the epaulments mentioned down to Lee's Mill. Below Lee's Mill the Warwick follows a tortuous course through salt marshes of 200 to 300 yards in width, from which the land rises up boldly to a height of 30 or 40 feet. The first group of works is at Wynn's Mill, where there is a dam and a bridge. The next is to guard another dam between Wynn's and Lee's Mills. (This is the point attacked by General Smith on the 16th ultimo. His object was merely to prevent the further construction of works and to feel the strength of the position.)

     A work, of what extent is not now known, was at the sharp angle of the stream just above Lee's Mill, and a group of works was at Lee's Mill, where there was also a dam and bridge. From Lee's Mill a line of works extends across Mulberry Island, or what is supposed to do so. At Southall's Landing is another formidable group of works, and from here, too, they extend apparently across to the James. These groups of field works were connected by rifle pits, trenches, or parapets, or nearly the whole distance. They are far more extensive than may be supposed from the mention of them I make, and every kind of obstruction which the country offered, such as abatis, marsh, inundation, &c., was skillfully used. The line is certainly one of the most extensive known in modern times. The country on both sides of the Warwick from near Yorktown down is a dense forest, with few clearings. It was swampy and the roads impassable during the heavy rains we have continually had, except where our own labors had corduroyed them. If we could have broken the enemy's line across the isthmus we could have invested Yorktown, and it must with its garrison have soon fallen into our hands. It was not deemed practicable, considering the strength of that line and the difficulty of handling our forces, owing to the impracticable character of the country, to do so.

     If we could take Yorktown or drive the enemy out of Yorktown the enemy's line was no longer tenable. This we could do by siege operations, and the result was in my mind a certainty. It was deemed too hazardous to attempt the reduction of the place by assault. The operations of the siege required extensive preparations, and the landing and bringing up of siege artillery by roads which we had to corduroy throughout their whole extent were in themselves heavy operations. The position of Wormley's Creek, with its numerous wooded ravines, which head near Yorktown, 1,500 yards (at that distance there was everywhere good cover in them), offered great facilities for siege operations, while it at the same time demanded great preliminary labor. Numerous bridges had to be built and roads prepared along the margin of the creek and up the ravines. Nearly 5,000 yards of road, mostly side cutting, with numerous crib-work bridges over intersecting ravines, were constructed. The mill-dam was widened for vehicles, and a crib-work bridge built at the 'old dam.' Three pontoon bridges, two long crib-work bridges, one floating-raft bridge, were constructed lower down (though not all maintained), and other bridges were in construction toward the mouth and over the South Branch.

     This preliminary work was so far complete on the 17th of April that it was deemed practicable to commence construction of batteries, and the following decided on:

     Battery No. 1, five 100-pounder Parrotts and one 200-pounder Parrott at Farinholt's house. Battery No. 2, fifteen guns, 4 1/2-inch 30 and 20 pounders, 1,500 yards from the Red Redoubt, and 2,000 yards from big gun. Battery No. 3, six guns, 20-pounder Parrotts, 1,900 yards from Red Redoubt. Battery No. 4, ten 13-inch mortars, Moore's plateau. Battery No. 5, four 20-pounder Parrotts near Warwick road.

     N. B.-- Six 20-pounders were put in this battery.

     Batteries Nos. 1 and 2 were immediately commenced and finished (essentially finished) in three days. No. 3 was commenced, but its construction was retarded by circumstances unnecessary to explain. The sites of Nos. 4 and 5 were not definitely fixed until two or three days later, and another, Battery No. 6, for six 4 1/2-inch ordnance rifled guns, was determined upon. Portions of parallel connecting Nos. 2 and 3, and from the left of the Yorktown road to No. 5 were commenced in the edge of the woods by daylight on the 25th. The same night a parallel was run through the open ground from No. 3 to connect with those portions just mentioned, and carried to a depth of 4 feet and a width of 6 feet, affording good cover. The same night a portion of parallel was commenced from near the point marked on the map as Redoubt C to near the head of the ravine toward the York River, and carried to dimensions to afford cover.

     On the night of the 27th a parallel was run across from the head of ravine in one night to the York River (or rather to the edge of the bluff), and on the night of the 29th a branch or boyau was run from this point 200 yards more advanced on the bluff, from which the whole area between us and the fortress was seen, the gorge of the first redoubt taken in reverse, and the Red Redoubt plunged into.

     I have not time to enter into the details of works and batteries, but will simple state that Battery No. 6 was changed into a battery for five sea-coast mortars, Battery No. 5 enlarged to contain eight 20-pounders, and Battery No. 3 enlarged to contain seven 20-pounder Parrotts. Batteries 7 and 8, for six 20-pounders each, were built to operate on the work at Wynn's Mill; Battery No. 9, for ten 10-inch siege mortars; battery No. 10, for three 100-pounder Parrotts and seven 4 1/2-inch ordnance; Battery No. 11, for five 10-inch sea-coast mortars; Battery No. 12, for five 10-inch and five 8-inch siege mortars; Battery No. 13, for three 30-pounder Parrotts and four 30-pounder Parrotts, directed at the redoubt at Yorktown works and on to batteries capable of being used on Gloucester; Battery No. 14 for three 100-pounder Parrotts and one 100-pounder James, to operate on Yorktown water batteries and Gloucester. Another 200-pounder Parrott was ordered to Battery No. 1.

     Redoubts A and B, for strengthening our line, were finished, Redoubt C well advanced, and Redoubt D just commenced on the night of May 3. A parallel had been run from redoubt A to Battery No. 5, obstructions and portions of parallel from Redoubt A to Batteries 7 and 8. The foregoing applies to the state of the works on May 3; not to the particular time at which they were finished.  A battery for two 8-inch siege howitzers was being commenced in a clearing south of the Wynn's Mill works, to enfilade that position, and two 8-inch mortars were to be put in position to operate on the works in front of General Smith's position.

     On the night of May 3 all of the batteries were armed (i.e., contained their armament) except three 100-pounders in No. 10, seven Parrott guns in No. 13, four 100-pounders in No. 14, and part of the sea-coast and siege 10 and 8 inch mortars were yet to be placed in battery.

     All would have been ready on the night of night of the 5th, and the fire would have been opened on Tuesday morning. The water batteries would have been enfiladed by Batteries Nos. 1, 13, and 14, while they were in direct line to receive all the shots of No. 10, which passed over the front of the work, and indeed No. 2 as well. The gunboats would have engaged and run past the water batteries, and opened a fire upon the rear of the town and enfiladed the ravine over the outlet of which the road from Yorktown to Williamsburg passes.

     When the number of our mortars and guns are considered, the great security with which they would have been worked (owing to their careful construction and the manlets provided for the embrasures), the positions which Batteries Nos. 1, 10, 13, and 14 occupied, the co-operation of the Navy, &c., it will be admitted, I think, that the enemy's positions had become untenable; that he could not have endured our fire for six hours.

     It should be mentioned that Battery No. 1 was opened on the 1st, and with great effect on the wharf (where the enemy appeared to be receiving artillery and stores) and the town.

     During the first opening of our parallels little effort was made by the enemy to interfere with our work by his fire, but after opening the parallel between the ravine and York River an incessant fire was kept up during the day with rifled projectiles, 8-inch shell, and solid shot, and 32 and 34 pounder shot, without retarding the work in the least or causing material loss of life. It is also a matter of surprise that, since our first appearance before Yorktown (April 5, and particularly since the 15th) the ravines and woods have been filled with men, night and day, making roads, building batteries, parallels, and guarding the works, the loss of life has been most trifling. I know not the exact number, but have reason to believe that it does not amount to a dozen. I can hardly conceive that the enemy should not have known how to use his curved fires with more effect upon those ravines. There was probably no very great supply of ammunition, and that was reserved for warmer work. His fire for the last two or three days was pretty brisk, however. During the siege operations General Woodbury, with his brigade, has been mainly engaged on the construction of roads and bridges, making gabions and fascines, and constructing Battery No. 4 (13-inch mortar).

     Captain Duane, with his command, and Lieutenants Comstock and McAlester, have superintended the siege works. All these officers have exhibited great energy, industry, and courage, and will be favorably mentioned by the commanding general, as also my aide-de-camp, Lieut. H. L. Abbot, Topographical Engineers, who has done most valuable service in the reconnaissances and determination of the positions of the enemy and our own works.

     Although it is next to impossible to fix by reconnaissances the exact trace of field works, our plans prove to be quite accurate, and the position of every one of the enemy's guns bearing on our own was marked.

     Captain Stewart and Lieutenant Farquhar have been at General Sumner's headquarters engaged in examining the enemy's positions along the Warwick and in strengthening our own and in constructing Batteries Nos. 7 and 8. Had the siege continued further they would have been brought to the front. I should mention that besides the siege work mentioned extensive boyaux of communication were made down the Peninsula between the York River and Wormley's Creek, as shown on the siege plan.

     I should also remark that the bateaux-bridge equipage constructed during the last winter has proved of infinite service, and I believe it is the only reliable military bridge. Such equipages as the India-rubber, or even the Russian canvas-boat bridge, are of very limited applicability.

     I send herewith four maps, viz: Map 1, siege plan; map 2, plan of Yorktown and Gloucester works, taken after our occupation (it must be borne in mind that there is a difference in the scale0; map 3, plan of the external works immediately connected with Yorktown; map 4, general topography and delineation of the enemy's line across the Peninsula. I regret that there is not time and means to prepare a complete record of this enormous system of defenses. They should form part of the record of the operations of the Army of the Potomac.

     The forcing of such a line with so little loss in itself is an exploit less brilliant, perhaps, but more worthy of study, than would have been a murderous assault, even if it had proved successful.

     I am, very respectfully, your most obedient,

J. G. Barnard,

Brig. Gen., and Chief Engineer Army of the Potomac

General Joseph G. Totten,

     Chief Engineer, &c., Washington, D. C.

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