September 22. 1807.
Though your Excellency has not honoured me with an answer, though my zeal and my efforts to benefit this country, whilst I serve also my own interest, could derive no sort of encouragement, as you will see, from the letter by which the Secretary at war has answered to two of mine and from his silence after receiving my reply, I am confident, Sir, that my present communication can be but agreable and acceptable to your Excellency, as its object is to prevent an immense waist of money and consequences worse yet to the first commercial city in particular and the united States in General, by demonstrating to you, Sir, the most undeniable defects and insufficiency of the plan of fortification which the corporation of new-york have published.
that plan, as you well know, Sir, consists in erecting batteries in new-york and on the islands in the bay, and making from red hook to a flat called oyster’s island, which distance is 3,900 yards, a range of blocks. on that flat a fort is to be built; a distance of 50 feet is to be left between the blocks, reduced to 30 by means of palissades 10 feet long fixed to each block. the blocks will be 10 feet below the water at low—and from 16 to 18 at high water. an entrance is to be left, to be filled at the approach of the Enemy with chevaux de frise.
Leaving aside what has been said of the delay of the blocks, of the effect of the tide against them, that of the obstruction to the tide &c, I make the following observations which any man, without being an Engineer, can comprehend.
I had only two ways, Sir, to render them usefull, either to publish them or to address them to you; I have thought I ought to prefer the last.
The Enemy, in that place, being not intirely shut out of the waters of new-york, has it fully in his power to come in small vessels or boats and insult the works on the islands where they may establish themselves to batter the town.
the same thing may be done by vessels of size inferior to frigates, such as the intended obstruction by blocks does not prevent from entering the harbour. they may venture to come in and penetrate into the north, but more easily, by the Cutter [mills channel], into the east river, where they can throw bombs and red balls into the town.
As the Enemy will be at liberty to use the same means proposed and intented against him, he will be able to destroy the blocks, perhaps at once, by the explosion of powder, at any depth in the water, or at least separate the frames where the rest will crumble.
the chevaux de frise intended to obstruct the entrance of the harbour for large vessels will offer but a weak resistance to the impulse of a ship of the line. besides the operation will require time and therefore must be put in effect at the mere appearance of danger; in which case the Enemy, at his pleasure, may by the show of an attack cause you to stop up that entrance and then retire. the inconvenience of such a situation will strike every one. if you remove the obstruction as often as the Enemy Withdraws, he can by that means keep you Constantly employed.
the fort at the entrance of the harbour, on oyster’s island, is acknowledged to be liable to be taken, but, as it can be commanded by one on bidlow’s island, it is supposed to be of little consequence because it cannot be retained; but let it be noticed that a temporary possession or even cessation of its fire would fully enable the Enemy to enter the harbour.
it is not true that the blocks will obstruct the passage of large ships. Suppose the Enemy coming with the tide, at about high water, and making directly for the blocks, in a line parallel to that of the blocks, each ship having a boat by his side and prepared to drop two anchors when she comes near the blocks. Suppose at the same time some other ships engage the fort to divert its fire and protect the ships now busy in passing through the blocks. I do not see what could prevent them from succeeding in a very short time by sliping their two cables astern, by the help of which the vessels can be guided to the greatest exactness between the blocks, a boat or other means being prepared to point out the channel. the palissades, below which they would want no more than four or six feet water, were thought too much in the way, they might be previously blown up without much difficulty.
how could in deed that manœuvre of the ships fail if undertaken, I shall not say at the other extremity of the line of blocks from the fort, but at only the middle of that line, which is 1950 yards, treble the distance of point blanc shot. there would be nothing against those ships leaving that fort behind them, passing along the batteries of the islands and the town, none of which fires at a distance less than 880 yards, and coming into the east or north river and laying the town under contribution.
from the history of all naval attempts against fortifyed ports we can readily infer that batteries firing at any considerable distance will never prevent the passing of ships. I do not know but I could defy any man to mention an instance of a ship of force being stopt in his way by batteries, and to be fully satisfied on the subject they must only attend to this observation. how often does it happen that a man of war in a line of battle passes along a whole line of twenty seventy four or three deckers and recieved the fire of about seven hundred guns within half musket shot, without losing even a top mast! how often has it happened that a ship of the line has sustained the steady fire of another till they came yard arm and yard arm and ultimately boarded and taken her, without being desabled from keeping the Sea! if a ship there can sustain such a constant and direct fire how little injury will she endure while passing before batteries at great distance! Unless some unknown eminent improvement in the use of the guns and mortars should ever happen to be found.
however they are now about constructing four batteries, on Governor’s and Ellis’s islands on the battery at new-york, and at the foot of duane street, to intercept the passage of ships into the north and east river, between new-york and governor’s island is one mile, and between any of the other points two miles, according to a map I have seen. every body must acknowledge that, even at the full distance of point blanc shot, which is about 650 yards no battery will stop ships of the line, and a fortiori when passing at nearly double and treble that distance, as it is the case with the four projected batteries. they are therefore, demonstrativly, of no use whatever.
No body to this day, Sir, that I know of, has started those objectives but myself. If that plan, the result of much reflection, consultation and deliberation, that plan though the best that could be adopted, is proved as I think it to be the case, intirely defective and inadequate, what shall be the consequence? What is left to be done?
Why then should I not be enabled to develope the sole plan on which the hope of effectually fortifying new-york may now rest? Why should I not be allowed to show that with much less perhaps than one fourth part of the cost of all those useless fortifications I can protect that town against any force?
If this examination of the plan now contemplated, which I have the honour to place under your eyes, Sir, might create in you an idea that some possible benefit may arise from listening to the man who, whilst he offers that examination to your Judgment, says he can give a much better plan, a plan applicable to all ports, very powerfull, very economical, no way injuring the harbour, of a more easy execution than any other, the sole infine which can answer especially the port of new-york, your Excellency would find the present conditions of my proposal for the communication of that plan, which I have lately much improved, in the subjoined sketch of an agreement, to which is annexed the copy of Mr. Dearborn’s letter and that of my answer.
to what I have said of the nature of my plan I shall add that the united States have no naval force on which to depend for the defence of their harbours but the gun boats and that there is no plan in which they can be of such eminent utility as in mine.
In Justice to the author of the one now acted upon I shall say that notwithstanding its defects and insufficiency it denotes upon the whole an able and skillfull hand. every thing that could be attempted with the means actually known and used has been proposed, but if they could have only inadequate and useless fortifications it would be better to have none at all. I am with Great respect, Sir, your most obedient humble servant
Du Buc de Marentille
DLC: Papers of Thomas Jefferson.