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Researching the Fortress of Louisbourg National Historic Site of Canada
  Recherche sur la Forteresse-de-Louisbourg Lieu historique national du Canada




Appendix 3 in:

King's Bastion Report VIII: 
A Survey of the Terrain of the Citadel Area Prepared 
for the Purposes of Archaeological Excavation
By John Fortier, July 30, 1965

Report H A 11 S1

Presently, the illustrations are not included here.
For these, please consult the original report in the archives of the Fortress of Louisbourg


December 1, 1964.


This paper concludes a preliminary investigation into the Demolition, based on the following sources:

1. Journal of the Demolition, compiled by the English Engineer officers. (Transcript)
2. MAC 229, MAC 141, MAC 141A
3. Gibson Clough's Journal. (pp. 21-39, period of 1760.)
4. Jonathon Procter's Journal. (Transcript of items extracted passim.)

My research was originally designed to create a chronology of the mining and demolition of the King's Bastion and, if possible, to determine something about the destruction of the Chateau as well. After several days with these documents, I can conclude with some finality that, for the Chateau at least, there is little to be learned from any of them. And, while this work has resulted in a rough chronology of the mining operations, I have tried to supplement its value by compiling some incidental information as a guide to anyone who may wrestle with this topic in the future.

It is impossible to determine anything about the Chateau from the Demolition Report or from the plans. Internal evidence within the Report strongly suggests that the only two comments that might in any way relate to the Chateau are actually in reference to the fortifications. [1] Moreover, even if we could establish the existence of a mine that had neither letter nor number, the placing of three mines at the right shoulder angle of the King's Bastion -- where only one should properly be marked --would make its final location uncertain. [2]

1. There is a reference on p. 170:  And there is an entry on p. 173:

"No. 32 R Offset Opned                    "E. R.  Offset 10 feet home
No. 34 LB 18 feet home                       -   L. Offset 10 feet home
-      R Offset Opned"                           G. RB 32 feet home."

The dash may represent an unrecorded mine, one not shown on the plans or mentioned elsewhere in the Report. The use of this sign as a ditto mark in other places, however, makes it more probable that the reference is to the mine immediately above.

2. This entire problem can become quite academic. The grouping of these mines at the shoulder angle where "I" should be, and the omission
of the letter "I" from any of them (MAC 229, MAC 141, MAC 141A), creates at least one area besides the Chateau where mines are not
properly located. With the evidence at hand, we cannot speculate any farther on this point.

This account suggests, therefore, in a negative way  that the Chateau was not mined, or that if it was, the project was regarded as separate from the destruction of the fortifications.

The reminder of this report deals with:

1. Additional information and nomenclature.
2. Galleries and mines.
3. Casemates.

1. Figure 1, on the page following, represents some of the basic term, and their use in the Demolition Journal, as I understand them. A considerable amount of secondary reading must be done before these definitions can be confirmed, and others added. It is impossible to determine from the Journal, for example, whether the mines were partially or completely encased by planks, and it is impossible to decide whether the frames were located 3 1/2 feet apart (p. 12).. 2' 8" apart (p. 16), or even 18" apart (p. 37). This is significant because it, in turn, bears upon our calculations on the length of the mines. It may be found that the frames were placed at different intervals in different mines, and that experience eventually showed an optimum distance of 18 inches. But this is one of the problems that must be clarified by other sources.


[Diagram Unavailable at this Time]

2. The Demolition began in the Princess Bastion and generally proceeded clockwise around the works. The King's Bastion was excepted, however, and its mines were next to the last to be sprung. As early as April, 1760, some debate had begun whether the Chateau should be destroyed as a fortification, or preserved as a dwelling, and this may explain the postponement of work in this area. (See file on "Chateau St. Louis, Notes from English Sources". period of 1760-1761.) Figure 2, a tracing from the Engineer's map of 1760, shows the mines, with the first and last recorded dates of the work done there.

A more detailed chronology of each mine is on page 6, figure 3. This includes every reference to the mines that I could identify. The statement that a branch or offset is so many feet "home" may imply that it has been finished, but there is no conclusive evidence on this point.

Figure 4 lists the number of durns (frames) used in each mine. Such totals were customarily included after the demolition of an area, and may afford a means of determining the length of each mine, once we know more about the spacing of the frames. Even now, assuming that the notation "home" does represent the completed lengths of a mine, the proportion of durns may reveal something about the nature of the soil. Galleries D, F, and H are shown on the plan (MAC 229), for instance, as being approximately the same. length. Yet there were 8 frames used in D, 4 in F. and 12 in H, by which we may infer that the soil in the right face near the salient angle was considerably less firm than the corrresponding area in the left face. (A factor which may, perhaps have exaggerated the effect of the English cannon during the sieges.)

Figure 5 lists the number of carpenters assigned to the Citadel mines. This may not be of great significance, but it does show the daily priority assigned to the work there.

On the afternoon of November 2, 1760, the mines in the King's Bastion were fired, and "answered Extremely well", except for two boxes, one, or both, of which were in the right and left offsets of the left branch of mine H. The charge in A may have been one of these as well, but this is impossible to determine from the wording of the transcript. It reads:

"The Citadell ... was Sprung ... Except Two Boxes to A the R & L of the L Branch of H to which the Sausage Did not Comunicate the fire to the fire to Reason of Som well [wet] that had dammaged it" (p..186)

The same day, Jonathon Procter recorded in his journal that, "They spring 6 mines in the Citadel but one of the boxes did not go off." (Nov. 2. 1760). This discrepancy is probably not significant. It is, more likely, the result of Procter passing on some hearsay information.


A. Left Branch 22 feet home - October 15th
(See also, Casemates, p. 10)

B. Right Branch 12 feet home - October 14th
Left Branch 22 feet home - October 15th
(See also Casemates, p. 10)

C. There seems to be no references to this gallery.
(See: Casemates, p. 10)

D. Right Branch opened - October 12th
Right Branch opened - Oct. 15 (sic)
Left Branch opened - Oct. 18th
Left Offset 14 feet home - October 22nd
Left Branch 13 feet home - October 24th
Right Offset 13 feet home - October 24th
Left offset 13 feet home - October 25th

E. Opened - September 27th; 26 feet home - October 4th
Right Branch exterior opened - October 4th
Left Branch opened - Oct. 9th
Right Branch 23 feet home - October 12th
Left Branch 9 feet home - October 12th
Right Offset 5 feet to the wall - October 18th
Right Offset 10 feet home - October 20th
Left Offset 10 feet home - October 20th

F. Opened - October 8th
Gallery 26 feet home - Oct. 15th
Right Branch 16 feet home - Oct. 21st
Left Branch 13 feet home - October 22nd
Right Offset 13 feet home - Oct. 25
Left Offset 13 feet home - Oct. 25th

G. Opened - September 27th; 32 feet home - October 2nd
Right Branch opened - October 9th
Left Branch opened - October 12th
Left Branch 32 feet home - October 14th
Right Branch 32 feet home - October 20th
Right Offset opened - October 21st
Left Offset 36 feet home - October 23rd

H. Opened - September 27th, 26 feet home - October 2nd
Left Branch opened - October 9th
Right Branch 38 feet home - October 13th
Left Branch 18 feet home - October 14th
16 feet to the wall - October 18th
Right Branch offset opened - October 19th
Left Offset 10 feet home - October 21st
Right Offset 14 feet home - October 24th

1. Opened - September 29th
Left Branch 62 feet home ? - Oct. 11th
1st [return, offset?] opened - Oct. 18th
word omitted here]
3rd offset 24 feet to the wall - Oct. 18th
1st return 20 feet home - October 24th

October 28th - All the Offsets in the Citadel Bastion Completed.
October 29th - Nov. 2 - Citadel mines loaded.
November 2nd - Citadel mines exploded.

Figure 4:

Summary of frames used in the Citadel mines.
(Demolition Report. p. 186)

      Gallery      RB Exterior      LD Exterior 
      D      8 5 5
  E 7 5 9
Mines -     F 4 2 6
  G 7 11 20
  H 12 37 20
  I 3 11 59

Figure 5.

Proportion of Carpenters employed at the Citadel mines
(Demolition Report, pp. 151-186)

3. The Citadel casemates were incorporated into the demolition procedures. Galleries A, B, C, and I used the casemates for access to the escarp walls. From the Journal, as well as from the plans accompanying, it would seem that charges were placed only in the casemates nearest the shoulder angles. Since 7 casemates were standing after the demolition (3 on the left and 4 on the right) this idea seems the more valid. (MAC 229, MAC 141, MAC 141A.

Since the casemate mines involved so little excavating, the Journal makes only a few references to their progress. The chronology of the casemates is, therefore, better considered as a supplement to that of the regular mines. In order the references are:

It would seem that the English found the casemates much more difficult to destroy than they expected, that none of the charges met with any great success. and that their entries in the Journal did not dwell upon these rather embarrassing failuress any more than was necessary. Indeed, it would seem that there was at least one more explosion needed here than the Engineers cared to record. We may assume, however, that the area around the shoulder angles was pretty well battered by October 16, and that the final detonations on November 2 were adequate enough that the remaining casemates were no longer a threat.

The Demolition Report is of greatest value for its description or the mines and the mining processes. It is, however, of much less use in determining the details of demolition in the areas that were not mined, and we can only assume that wherever charges were not planted, the fortifications were dismantled by hand.

The 1760 plans reveal that all of the cater defences were reduced. The townward fortifications around the King's Bastion are not shown, but they must have received the came treatment. This included the destruction or large segments of the counterscarp and the revetments of the glacis, as well as the levelling of such earthen defences as the crest of the glacis aid the edge or the terreplein of the covered way. Wherever a complete job of levelling was not done, the edges were dug away until they were practically featureless. (The results are shown quite clearly in the top view and profiles or MAC 229.)

The work consumed great quantities of wood. Several houses as well as the gun platform and the wooden revetments for the walls themselves, were pulled apart to provide lumber for the mines. (pp. 4-5, 69, 78, 144). Indeed, every wooden structure ms liable to be dismantled ,and by July 8th, so many palisades had been used that the carpenters were forced to take down the few that still remained around Cap Noir (p. 66).

At one point, an experimental trench was dug in one or the places of arms. It was made in the same shape as mine  #6, and its branches and chambers were in the same relation to each other as the prototype -- except for the right interior branch, which was placed on the left side of the trench because the ground on the right was too difficult to dig. The trench itself was 2 1/2 feet wide and 1 1/2 feet deep. The branches were 2 feet wide and 1/2 foot deep. The work seems to have been fairly extensive; 32 men were occupied with the digging for two or three days. "Sausage boxes" and powder charges were finally laid along the bottom of the excavation. and the top was, filled over with sand bags.

The experiment was conducted to determine whether the "badness" of the air and the acute angles within the mines did not prevent the charges from igniting simultaneously. On July 22nd, the trench was fired, "but the Quantity of Earth placed above the Sausage being no More than a foot and a half and the Quantity of  Powder containd. in a foot of Sausage being 9 ounces, as soon as the Fuze Communicated the fire to it, it raised the Earth, and Stones all along as it went to such a degree that it was hard to say whether the Communication of the fire from the Different Branches to the Chambers was Instantanious or not". (pp. 79-84) In any case, the traces of this experiment may still remain.


It has been suggested that I comment on some of the more significant aspects of this period and the sources concerning it.

The Demolition Report is a difficult source to work from. It is full of grammatical errors, mis-spellings and inconsistencies, and its entries become even less precise after the work of demolition is under way. For farther research, it is imperative that we attempt to secure a microfilm or photostat copy of the original, to use in lieu of our transcript. This must certainly clarify some of the problems which arise in a source where every remark is significant.

Even with the copy of the Report we now have, however, it will be possible to duplicate the findings on the Citadel for the entire line of fortifications. A chronology of each mine, and a comparison of size and design could be prepared, although this would be a time-consuming effort, and perhaps not that rewarding in return.

A considerable amount of secondary reading will be necessary before the technique of the demolition mining can be determined. The descriptions in the Report were addressed to other Engineer officers, and they are not easily understood by anyone else. This subject is important, however, and of real relevance to our research on the fortifications, and the Demolition Journal is a muddled, yet indispensable, base from which to begin further study.

Gibson Clough's Journal is not sufficiently detailed to be of use in this area, but Jonathon Procter's is, and a copy of the original, or a completed transcript, should be obtained if possible.

The number of workmen employed, and their distribution at each mine, or as carpenters, is something that can be studied in some detail from these sources. The role of the New England levies, as well as that of the regulars, Marines and Engineers night also be a worthwhile area of study.

A brief search through the Report and plans will further show which areas were mined and which were demolished by hand,, and such knowledge,, especially if made into a separate report, might be of ccontinuing value.

Another study could be made on the tools used in the demolition. The Report describes some improvements that were made by the miners in the equipment at Louisbourg. And Clough's Journal includes a page of drawings on such items as wheel-barrows, fuse, and priming iron.

An inset plan in MAC 229 shows a top view of the entire line of fortifications as they appeared after the demolition was complete. If we could obtain some aerial photos from an equivalent height, the comparison might reveal several points of interest for our post-1760 histories of the works.

It should be mentioned, finally, that the first pages of the Demolition Report contain detailed measurements of the fortifications around the Queen's and Princess Bastions, and any research in this area will be greatly facilitated by the references to be found there.

I have come to regard the demolition project as a particularly interesting subject, and I will remain more than willing to expand upon my present findings, or assist anyone assigned, to this area, at any point in the future.,

John Fortier.