28/07/2026
From the Saddle to the Drawing Board -
Captain William Terry and a remarkable collection of Napoleonic military-engineering drawings
Among the most historically compelling discoveries in our forthcoming auction on Saturday 1st August 2026 is a collection of large original military-engineering drawings dating from the height of the Napoleonic Wars.
Executed in pen, ink, pencil and coloured wash, they depict bastioned fortifications, defensive earthworks, siege trenches, artillery positions, elevations and measured cross-sections. Several are signed: “William Terry, Captain, Royal Regiment of Horse Guards” and dated between September 1809 and March 1810.
These are not simply decorative maps. They are the technical studies of a British cavalry officer learning the complex science of defending—and attacking—a fortified position at a time when Britain remained at war with Napoleon.
Who was Captain William Terry?
Surviving military commissions trace William Terry’s advancement through one of the most prestigious regiments in the British Army. He was appointed Cornet in the Royal Regiment of Horse Guards on 1 October 1803, promoted Lieutenant on 4 April 1805 and Captain on 6 August 1807. Terry died in January 1864.
One of his lieutenant’s commissions, signed by King George III on 4 April 1805, has also appeared separately at auction. It formally appointed Terry as a lieutenant in the Royal Regiment of Horse Guards and bears the King’s signature and the countersignature of Lord Hawkesbury.
The Royal Regiment of Horse Guards was popularly known as “The Blues” and occupied a position of considerable status within the British cavalry. Terry was not a professional military engineer in the usual sense, but a cavalry officer who appears to have received advanced instruction in surveying, military drawing and fortification.
Britain under threat
When Terry entered the Army in 1803, Britain was again at war with Napoleonic France. The danger of invasion was not merely theoretical. Napoleon assembled a large army on the Channel coast, while Britain mobilised regular troops, volunteers and defensive preparations throughout southern England.
In this world, military drawing was far more than an artistic accomplishment. Before photography, aerial reconnaissance or electronic communications, an officer’s ability to survey the landscape and represent it accurately could influence the movement and survival of an army.
Military plans recorded roads, rivers, hills, bridges, settlements and possible defensive positions. They showed where troops could camp, where supplies might be found, how artillery might be positioned and how an enemy could approach.
Another surviving group of maps drawn principally by William Terry in 1809–10 demonstrates this work. Those sheets record troop positions around High Wycombe, routes of march, winter quarters, advance guards and even local populations, cattle and supplies of forage. They have been interpreted as possible preparations for the defence of the district against French invasion.
The science of the fortress
The collection offered at Wincanton Auctions concentrates upon the theory and construction of fortified places.
To modern eyes, the angular forms of a bastioned fortress can appear almost ornamental. In reality, every projection, ditch and defensive line was carefully calculated to expose an attacking force while allowing defenders to protect one another with overlapping fields of fire.
The drawings include plans and elevated perspectives of bastioned fortifications, together with profiles through ramparts, parapets, ditches and covered ways. They also show batteries, redoubts, bridges, defensive structures and systems of zigzag trenches approaching a fortress.
The finest sheets are particularly impressive in scale, some measuring approximately 130 centimetres across. Pink, blue and grey washes distinguish masonry, earthworks and structural elements, while technical annotations and measurements cover the surfaces.
In several examples, the underlying pencil framework remains visible beneath the finished ink and wash. This allows us to follow Terry’s working process as the complete design gradually emerged from a carefully calculated network of lines and angles.
How was a fortress attacked?
Several drawings reveal the formal science of siege warfare.
An attacking army could not simply advance directly towards a well-defended fortress. Instead, troops constructed a series of protected trenches known as parallels, connected by angled approach trenches called saps.
The first parallel established the attackers within artillery range. Zigzag trenches then advanced towards the fortress without presenting a long, straight target to defensive fire. A second and third parallel brought troops and guns progressively closer until artillery could breach the defences or an assault could be attempted.
Terry’s plans illustrate these systems from above. Radiating construction lines show the calculated relationship between the fortress, the besiegers’ trenches and their fields of fire.
Another sheet presents cross-sections through temporary siegeworks, including communication trenches, cavalry positions, redoubts and a ricochet battery.
A ricochet battery was intended to fire along the length of an enemy rampart, causing shot to bounce repeatedly through the defenders’ position. It was a specialised technique requiring careful calculation of range, elevation and angle.
Why are the annotations in French?
Many of Terry’s technical annotations are written in French. This may initially seem surprising in drawings made by a British officer during a war against France. However, French was widely used as an international language of educated society and military science.
Many of the most influential European systems of fortification had been developed and refined by Continental engineers, most famously the French fortress designer Sébastien Le Prestre de Vauban.
The terminology suggests that Terry was working from an established Continental system of military-engineering instruction, possibly copying or adapting recognised exercises as part of his professional education.
This does not lessen the significance of the drawings. The surviving pencil lines, corrections and partially completed constructions show how a British officer learned to transform geometrical theory into a practical defensive design.
Made during the Napoleonic Wars
Several sheets bear dates in Terry’s own hand:
1 September 1809
4 September 1809
15 September 1809
5 October 1809
25 October 1809
14 March 1810
The paper provides further supporting evidence. Several sheets bear a watermark for James Whatman, Turkey Mill, Kent, 1808.
Whatman paper was among the finest English drawing papers of the period. The watermark corresponds closely with the handwritten dates and supports the conclusion that the drawings were created as a coherent sequence during 1809–10.
One sheet is marked Plate 9 and another Plate 10, indicating that they were originally part of a larger ordered course or portfolio. Other related drawings may therefore remain undiscovered or may have become separated during the following two centuries.
A cavalry officer with an engineer’s eye
The most intriguing question is why an officer of the Horse Guards produced such detailed engineering work.
An early nineteenth-century officer was expected to understand considerably more than drill and horsemanship. Surveying, reconnaissance, topography, drawing and the selection of defensible ground were valuable military skills, particularly for an officer required to report upon unfamiliar terrain.
Terry’s other surviving maps reinforce this interpretation. They show that he could record troop movements, camps, local resources and the geography of a district, as well as the theoretical design of fortifications.
His surviving work therefore bridges two military disciplines: the mobility and reconnaissance associated with cavalry and the measured geometry of the military engineer.
It is possible that the drawings were produced during a formal course of instruction or under the supervision of an experienced engineer. At present, however, no documentary evidence has been identified naming the particular institution, instructor or fortress model from which they were derived.
They should therefore be understood as advanced military-engineering studies rather than confidently identified as plans for one particular fort.
More than maps
What makes the collection so appealing is its combination of historical importance, technical precision and visual impact.
The sheets were made during the Napoleonic Wars by a named British officer whose rank and commissions can be independently documented. They reveal military thought before photography, aircraft or digital mapping, when a steady hand, a ruler, a compass and a knowledge of geometry were essential instruments of war.
The folds, handling marks and unfinished construction lines are not merely imperfections. They are evidence of use and allow us to observe Captain Terry’s working methods more than two hundred years later.
The pencil framework beneath the ink, the repeated angles, measured profiles and carefully applied washes preserve the gradual emergence of a complete fortress from a network of mathematical lines.
Today, the drawings remain both impressive works of draughtsmanship and remarkable survivals from Britain’s long struggle against Napoleon.
Offered at Wincanton Auctions
The Captain William Terry military-engineering drawings will be offered as individual lots in our General Sale on: Saturday 1st August 2026, commencing at 10.00am
Viewing will take place on: Friday 31st July 2026, 10.00am–4.00pm
The full catalogue, photographs and individual lot descriptions are available at: www.wincantonauctions.com
Wincanton Auctions Ltd
Bennetts Mead, Southgate Road
Wincanton, Somerset BA9 9EB
01963 361611
Holding monthly Online and Live General, Specialist and Antique sales. Open Mon-Thurs 10am to 4pm
