Sir Marc Isambard Brunel (April 25, 1769 – December 12, 1849) was a French-born engineer who eventually settled in the United Kingdom. He preferred the name Isambard, but is generally known to history as Marc, to avoid confusion with his more famous son Isambard Kingdom Brunel.
The younger son of a farmer in Normandy, initially he was set to train for the priesthood, but had a more practical mind, and became a naval officer cadet instead. In 1793, in the face of the French Revolution, he fled to the United States, becoming chief engineer of New York. In 1799 he moved to Britain, which presented greater opportunities for the development of mass-production machinery, and which was the home of his future wife Sophia Kingdom. His initial success was with a method for production of rigging blocks (pulleys) for the navy at the Portsmouth Block Mills: (his collaborators included Samuel Bentham and Henry Maudslay).
His most notable achievement was the Thames foot tunnel, which was built for horsedrawn traffic but due to bankruptcy was first used by pedestrians, and now carries the East London Line of the London Underground. In the construction of the tunnel he pioneered the use of the tunnelling shield, a moving framework which protected workers from tunnel collapses when working in water-bearing ground. The tunnel was authorised by Parliament in 1824, and started in 1825, but due to technical and financial difficulties was not opened until 1843. He was knighted for his contribution to engineering in 1841 and was elected to the Royal Society. Like his son he is buried at Kensal Green Cemetery, London.