High Quality Content by WIKIPEDIA articles! Colonel Patrick Mackellar (1717 – 1778) was a British army officer and military engineer who played a significant role in the early history of North America. He was the deputy chief engineer at the Siege of Louisbourg (1758) and the chief engineer at the siege of Quebec in 1759. In later years he was responsible for the design and construction of the town of Es Castell on the island of Minorca.