Jean Le Michaud d'Arçon

Jean Claude Eléonore Le Michaud d’Arçon (18 November 1733 - 1 July 1800) was a French general, specializing in fortification. His designs include the forts at Pontarlier and Fort-Dauphin in Queyras.

He was the son of a lawyer who also wrote several short works on costume of the Franche-Comté. Jean Claude was born in Besançon and was originally intended for a career in the church - he was sent to view a parish to win him round to this career, but he was keener on an army career, drawing and mapping fortifications instead of studying Latin. When someone was sent to draw his portrait for his parents, he opted to be shown in the dress of an engineer not a clergyman and his father agreed to support his choice of career. He studied at the École royale du génie de Mézières in 1754 and was made an engineer-in-ordinary the following year, fighting with distinction in the Seven Years' War, particularly in the defence of Hesse-Kassel in 1761.

In 1774 he was charged with mapping the southern Alps, the Jura and the Vosges. To speed up his work he invented a new form of ink wash painting with only one brush. In 1774 and 1775 he got into a debate with comte de Guibert over ordre profond versus ordre mince and ended up publishing two pamphlets entitled Correspondance sur l’art militaire which (as with all his writings) showed many new engineering ideas but also several neologisms and mistakes.

Attached to marshal Broglie's force in 1780, he looked for ways to win the siege of Gibraltar. Attacking by land was impossible and so d’Arçon began designing "unsinkable and fire-proof batteries" intended to breakthrough from the coast in tandem with other batteries advancing the British rear from inland. These would have strong thick wooden armour and water pumped around them to avoid fire breaking out, whilst old cables would also deaden the fall of enemy shot and their ballast would counterbalance the guns' weight. They would also be supported by ships of the line and bomb ships, who would try to draw away and split up the enemy fire. Five machines with two rows of batteries and a single row of five batteries would make up a total of 150 guns.

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