Official Records of the Rebellion

No.2. Reports of Brig. Gen. John G. Barnard, U. S. Army, Chief Engineer of operations from May 23, 1861, to August 15, 1862.

[p.127: COMPARES TYPES OF PONTOON BRIDGE]

The pontoon equipage which accompanied the army was got up, as already mentioned, by Lieutenant-Colonel Alexander, assisted by Capt. J. C. Duane. The former had acquired an enviable reputation as the builder of the Minot’s Ledge light-house, possessed great practical ingenuity, and had had the means of knowing the best results arrived at in other services in this branch of military art. Captain Duane possessed a more extensive and thorough practical and experimental knowledge of military bridges than any other man in this country. They gave, after full consideration of the subject, their preference to the French system. Even had they adopted this system blindly, because it was French, they would not have been without solid reasons, for the French have studied and experimented upon the best systems known to the world. Whatever may be said about the difference in the character of the country, roads, &c., the thing to be done here and in Europe (now that our armies have assumed European magnitude) is essentially the same. But these officers had before them the best modern inventions of Europe and America. The India-rubber pontoons they knew thoroughly; corrugated iron bodies and countless other inventions of American genius were before them, and the former experimented upon.

[p.128]  

My own prepossessions had been in favor of the Birago system of sectional pontoons and Birago (so called) trestles. The experience we had proved the wisdom which adopted the system in question. Not to advance, by any means, that nothing better can be found (the substitution of iron for wood was one of the probable improvements well understood by the officers named, but not at that time adopted for substantial reasons), it is enough to say that the French pontoon was found to be most excellent, useful, and reliable for all military purposes. They were used by the quartermaster’s department in discharging transports, were precisely what was needed for the disembarkation of General Franklin’s division, constituted a portion of the numerous bridges built over Wormley’s Creek during the siege of Yorktown, and were of the highest use on the Chickahominy, while over the Lower Chickahominy some 75,000 men, some 300 pieces of artillery, and the immense baggage trains of the army passed over a bridge of the extraordinary length of nearly 650 yards—a feat scarcely surpassed in military history.

The Birago trestle, of which I had formed so high an opinion, proved itself dangerous and unreliable—useful for an advance guard or detachment, unfit in general for a military bridge. Of the American India- rubber and the Russian canvas pontoon we had no fair experiment. They may both be useful, but, again, I think not reliable for a military bridge, considered in all its aspects and uses.

The weight of the French pontoons is objected to, but a certain floatation power is required which it is not easy to get, nor are the ways unobjectionable which seek to get it with less weight, and the vehicle which carries it is not heavier loaded than other vehicles of an army train. Less length would certainly make it more manageable on our narrow roads, while for advance guards and dashing minor enterprises greater lightness is requisite. Perhaps an iron sectional pontoon may be contrived which will meet these requirements, but prudence demands that the safety of an army shall not be jeopardized by giving it a bridge which experiment has not fully tested.

American genius is fertile in this as in all other expedients, but no genius can provide for an object which is not understood. The numerous proposers of flying bridges forget that if a military bridge is intended to be carried with an army it is also intended to carry an army, its columns of men, its cavalry, its countless heavy wagons, and its ponderous artillery. It must carry all these, and it must do it with certainty and safety, even though a demoralized corps should rush upon it in throngs. No make-shift expedient, no ingenious inventions not tested by severe experiment, nor light affair, of which the chief merit alleged is that it is light, will be likely to do what is required, and what the French pontoon has so often done.

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