150 years ago: Canvas or wood for your pontoons?

As our attention turns to Fredericksburg, the topic of pontoon bridges enters the sesquicentennial threads.  I’ve discussed the nature of constructing these bridges in detail, with respect to those placed at Edwards Ferry in June 1863.  We think of the wooden pontoons most often within the context of the Civil War.  Big wooden boats like the ones on display at Chatham overlooking Fredericksburg today.

Chatham 13 Dec 014

These were not the only type of boats used for pontoon bridging during the Civil War.  One alternative was a frame, either wood or iron, with either canvas or rubber covering.  An example of the frame with canvas type appears in a wartime photo taken at Rappanannock Station in 1864.

Almost looks like it was setup on some display just for the benefit of the photographer!

The canvas boat was of course lighter and easily broken down for transport.  But there were some down sides to canvas boats.  A message from Major (or was it Brigadier?) General Horatio Wright to Major General William Rosecrans in early December 1862.

I’m pulling this message out of context, so some background is in order.  Considering his orders and line of march, Rosecrans decided the Army of the Cumberland, or Fourteenth Corps if you prefer, needed a pontoon bridge set.  He figured on about 700 feet of bridging.  Authorities in Washington approved, and directed Rosecrans to order the equipment from Cincinnati, where engineers in General Wright’s Department of the Ohio could supervise the outfitting.  There was some back and forth about the type of boat to issue – wood or canvas.  The preference of the Army’s engineers is apparent in Wright’s response on December 7, 1862:

Canvas boats are not so reliable as wooden ones. Unless great care is used, canvas necessarily mildews and then soon rots. If used by soldiers for shelter, it would soon become damaged for boats. It is not entirely water-proof, even after it lies in the water some time. It is doubtful whether canvas boats are as reliable in ordinarily rapid streams as wooden ones, especially if the bridge’s required to serve a long time, as on a line of communication. Canvas is more easily punctured and worn by floating bodies, and requires to be taken out of the bridge to be well repaired. It takes more time to unload, put together, and launch a canvas boat than to simply unload and launch a wooden one. According to Duane’s book, a canvas boat train requires as many wagons to transport it as a wooden one. Wooden boats can be produced here as rapidly as canvas ones, and are rapidly calked and repaired when leaky, provided they are made of seasoned timber. Wooden boats are much better for use as boats, or to combine into rafts. Unless for a very short campaign, with careful and experienced engineer troops, I would advise the adoption of wooden boats. Buell’s pontoons were made of green lumber. We can get seasoned now. Shall I order wood or canvas?

The reference of “Duane’s book” is, I believe, to the Manual for Engineer Troops by Captain James C. Duane.  As an instructor on various engineering topics, Duane had the opportunity to research pontoon bridging, compare to practices in other armies, and experiment with different materials.

I could probably pull another dozen pages from the manuals and wartime accounts to further illustrate respective advantages and disadvantages of wooden boats vs. canvas frame boats for pontoons.  Wood, at least seasoned wood, was more durable and required less maintenance.  Not mentioned, but cited in the engineering manuals of the day, wood stood up well against rocky stream bottoms, where canvas ripped.

With respect to the number of wagons needed, there’s a lot of other factors that were not considered with Wright’s response.  Duane indicated a wooden boat, or “French style,” pontoon train required 34 wagons each loaded with a pontoon boat, seven balks, numerous lashings, oars, boat-hooks, and an anchor.  On the other hand the canvas train required 29 wagons each with a canvas pontoon, trestle, with balks, oars, and boat-hooks.  Notice the canvas boat wagons included some, if not all, the superstructure of the bridge.  The wooden pontoons, being fixed size and structure, were much more bulky on the road.  The wagon carrying the canvas pontoon was smaller and lighter.

Wartime experience called upon some reassessment in regards to the preference of materials.  In 1869, a board of engineers submitted a new manual covering bridging operations (eventually approved and published in 1870).  The board noted:

With regard to the canvas boat, it soon became apparent that it was precisely what we required for our advance-guard train. It is light, simple, strong, easily repaired, and when packed can safely be transported with the superstructure of the bridge as rapidly as any column of troops can move.

The board of officers submitting this manual included Duane.  The board also noted that the canvas bridging also worked well for expedient ferry operations.

I’ve found no direct record to confirm the type of pontoons delivered to Rosecrans.  The Army of the Cumberland used both types at times later in the war, for what it is worth.

But turning back to the Eastern Theater for a moment – what if  Major General Burnside’s pontoon train had included a set of these “advance guard” canvas pontoon boats?


Disloyalty in the Ordnance Department? The case of William Maynadier

In the tense days of December 1860, Captain William Maynadier became a central figure in the correspondence concerning the disposition of military stores.  Maynadier, a West Point graduate of 1827, was at that time the assistant to the Chief of Ordnance, Colonel Henry K. Craig.  Maynadier had served in that capacity since 1842.   In November 1860, Craig was briefly relieved at the head of the Ordnance Department, with Maynadier then serving as a temporary chief.  This made Maynadier the “man in the middle” as political leaders sought information about the status of forts, arsenals, and armories.  Maynadier also issued orders in the name of the Secretary of War, John Floyd, and Colonel Craig.

William Maynadier

One set of orders issued by Maynadier on December 22 called for Allegheny Arsenal, outside Pittsburgh and commanded by Major John Symington, to forward heavy guns to forts along the Gulf Coast.  Order for Supplies No. 666 and No. 667 called for 10-inch and 8-inch columbiads along with 32-pdr seacoast guns to arm the forts at Ship Island, Mississippi and a fort at Galveston, Texas.   After drafting these orders, Maynadier sent a note to Secretary Floyd confirming the action:

I have the honor to report that in compliance with your directions I have ordered forty-two columbiads and four 32-pounder guns be sent to the fort on Ship Island; also seventy columbiads and seven 32-pounder guns to the fort in Galveston Harbor.  These cannons have been ordered from the arsenal near Pittsburg, and directed to be consigned to the engineer officer in charge of the respective forts, viz: Those for Ship Island to Lieut. F.E. Prime, and those to Galveston to Lieut. W.H. Stevens, of which these officers have been advised.  These pieces of ordnance belong to the regular armament of the respective forts.1

This correspondence seems mundane on the surface.  The Army’s top mission in those pre-war days was seacoast defense.  So putting guns in forts was just normal business.  But the forts mentioned in the correspondence were not complete by any measure.  Furthermore, had theses guns been transferred as ordered, they would shortly have fallen into the hands of Confederates.  Later, as events played out through 1861, Maynadier’s orders looked suspicious to say the least.

In July 1861, Representative John F. Potter, of Wisconsin, convened a select committee to investigate the loyalty of government employees.  The committee considered some 550 charges made, including those against military officers.  Maynadier’s pre-war orders came under scrutiny of the committee.

By the time the committee began investigations, Maynadier was a Lieutenant-Colonel at Frankfort Arsenal, very much involved in the war effort.  So you can see where this might cause some embarrassment at the War Department.  The committee would review two main charges against Maynadier.  The first centered upon the transfer of ordnance mentioned above.  The second regarded the sale of obsolete muskets to parties associated with the secessionists.  This later charge, much like the first, stemmed from Maynadier’s administrative role in the Ordnance Department.  In the 1850s the Army realized the need to upgrade its stock of arms.  In an effort to salvage what it could, stands of old arms were sold to provide supplemental funding.  The charge was Maynadier worked deals to sell those arms, in excess of what was directed and at low prices.2

Regarding the forts, Horatio Wright, who’d been a captain at the time of correspondence but was a brigadier general of volunteers in the summer of 1861, testified that he had conversed with Maynadier in December 1860.  Specifically, Wright recalled he had pressed the point about the status of the forts, stating the Ship Island fort was incomplete and at Galveston ground hadn’t even been broken. To arm forts, the Army normally waits until the works are completed, then dispatches the guns (makes sense – build the house first then move in the furniture).  In this case, the process was apparently being reversed.  This prompted Wright to inquire with his boss, General J.G. Totten.3  Effectively the evocation of such red-tape voided any orders by Maynaider.

The sale of obsolete muskets was a bit more complicated.  Craig, an old and sometimes cantankerous veteran of many years of bureaucracy, happily pointed out that in his absence from the Ordnance Department, Maynadier had sold large quantities of muskets to southern interests.  Reviewing the testimony, the committee reached the conclusion,

Here, then, we have incontrovertible evidence that, within a month after Major Maynadier was placed at the head of the ordnance department, 20,000 stand of arms were sold to the rebel enemies of the country; and that 100,000 to 250,000 stand were bargained for, evidently with the expectation that they were to go into the same hands.4

On the surface, these charges seemed to hold water.  The War Department had little choice but to suspend Maynadier.  In the face of these charges, Maynadier sent a reply to the committee in February 1862.  The gist of his defense was, “I was acting under orders.”  Regarding the arming of the unfinished forts, Maynadier reasoned:

The order was a legal one, and the full and perfect authority of the Secretary of War rightfully to give the order was unquestionable.  It would have been a high military crime to have refused or neglected to execute the order, and it would have been an act of gross impertinence and insubordination in me to have questioned the Secretary of War, as to his reasons or motives for sending the cannon.  In truth, it never entered my mind, at that time, that there could be any improper motive or object in the order; for, on the question of Union and secession, Mr. Floyd was then regarded, throughout the country, as a strong advocate of the Union and opponent of secession.5

Maynadier went on to disagree with Wright on several particulars regarding their coordination.  But the basic details remained – the forts, being unprepared, did not receive guns.

Maynadier’s response to second charge continued the “I was ordered” defense.  He pointed out the laws and regulations governing the sale of condemned, obsolete weapons.  And he continued by indicating the particulars of transactions from 1857 to 1861.  The Army first offered, as Maynadier indicted, the arms up for bid to perspective buyers.  None of the bids met with the Army’s approval.  At that point, Secretary Floyd authorized sales at a price more acceptable to the Army.  With regard to the bargaining for 100,000 or so muskets, Maynadier pointed out a proposed sale of weapons to a Mr. A. A. Belknap was at a unit cost below what the Secretary had set.  When Maynadier brought that issue to the fore, the deal fell through.6

Maynadier’s defense also speaks to the internal politics within the Ordnance Department.  Craig, a long serving officer of the ‘old-old Army’ was at odds with some of the younger set (we might put Rodman in that company, but certainly must put the likes of Joshia Gorgas in that set).  Maynadier firmly pointed the finger at his boss, inquiring why similar charges were not levied “against Colonel Craig for obeying the orders of the same person to sell 20,150 [muskets], mostly to the States of Virginia and Alabama, and to a firm in Louisiana.?”7

Closing his defense, Maynadier noted his long and continuing service to the country.  He further added that two of his sons, and a son-in-law, were serving the country, at that time (Henry E. Maynadier was in command of the Mississippi Mortar Boats at the time of writing.  And His son, William Murray, went on to serve with some distinction, in particular at Antietam.).  While it would be a nice, romantic notion to say that carried the day, reality is changes in the political winds and war situations worked in Maynadier’s favor.

Secretary Simon Cameron, the target of some of the congressional heat, resigned in January, having spoken in favor of arming slaves.  His replacement, Edwin Stanton, offered some sacrificial lambs to the Potter Committee without giving up useful hands, such as Maynadier.  At the same time, with Floyd making blunders in the field (Fort Donelson), on balance anything lost to wrong-doing in 1860 was seeming like a fair trade.

Maynadier continued to serve in the Army.  In his late fifties by that time, he was too old for field service and continued with postings at arsenals.  By 1864 he was the inspector of arsenals and depots.  He died in 1871 and was buried in Washington, D.C.’s Oak Hill Cemetery.


  1. The correspondence is enclosure 3 of a set provided to the Potter Committee on October 28, 1861.  See the Official Records, Series I, Volume 53, Serial 111, pages 504-505.
  2. Loyalty of clerks and other persons employed by the government,” Reports of Committees of the House of Representatives made during the Second Session of the Thirty-Seventh Congress, 1861-62,  Volume 3, No. 16Washington: Government Printing Office, 1862, pages 16-20.
  3. Ibid, page 16-17.
  4. Ibid, page 20.
  5. Reply of Lt. Col. Maynadier to the charges in the report of the Potter committee, Washington: H.S. Bowen, 1862, page 4.
  6. Ibid, pages 6-7.
  7. Ibid, page 7.