Dunkirk (in French 'Dunkerque') was much fought over by European powers in the sixteenth and seventeenth centuries, but France finally recovered the town in 1662. King Louis XIV built important fortifications there to make the port a safe base for Jean Bart and other French corsairs who preyed on foreign ships.
However, by Article 9 of the Treaty of Utrecht 1713 Louis XIV was forced to demolish the fortifications and the harbour. Brigadier John Hill was appointed to command the British troops sent to Dunkirk to hold the town as security for the execution of the terms of the treaty. Hill, together with Major Sir James Abercrombie, Commandant of the garrison at Dunkirk, Jaspar Clayton, Governor of the citadel, and John Armstrong, Chief Engineer, were appointed commissaries to ensure that the demolition was effected.
The work proceeded slowly, and the French tried to circumvent the terms of the treaty by building a new harbour at Mardyke. Article 4 of the Defensive Alliance concluded in January 1717 at the Hague between Great Britain and the United Provinces of the Netherlands stipulated that Great Britain would do all in its power to destroy the harbour at Dunkirk and the new harbour at Mardyke. As a consequence, new commissaries were appointed to act as inspectors and 'eye witnesses' to ensure that the work was done as required: Colonel John Armstrong and Jacob Acworth (Surveyor of the Navy), and Colonel Thomas Lascelles (Engineer) if one of the other two was unable to act for any reason. By July 1717 the works at Mardyke were being destroyed.
However, in 1719 intelligence was received that the French were planning to undertake works at the Bergues sluice and make a free communication with the old harbour. The British continued in their efforts to prevent the French from re-establishing access to the town from the sea, and the French made sporadic attempts to recreate the link, including deepening the Mardyke canal and undertaking other works at Furnes and Bergues.
Joseph Day was appointed to assist Lascelles as an engineer in 1727, and when Lascelles left Dunkirk, Day remained to report to Whitehall on events in the town, though he was given no formal commission. In 1737 it was reported that the French were planning to build a port at Gravelines, and work was under way by 1738. In 1740 Day died and John Laye was appointed to succeed him.
France was not allowed to rebuild the fortifications of Dunkirk until late in the eighteenth century.