Chagres was built by the Spanish on the Panama isthmus in the early sixteenth century, an important stop on the transatlantic route for bullion fleets. It was attacked by Admiral Edward Vernon in 1740, a year after his victory at Portobelo, but with less success. Vernon’s destruction of Portobelo allowed Chagres to become the most important Atlantic port in the country. By the time this map was made, its importance had declined. The Fort of San Lorenzo shown on the map was mainly used as a prison.

The survey was carried out by Captain J. A. Lloyd, who was appointed Surveyor-General for Mauritius in 1832; and engraved by James Gardner, who had worked under Thomas Colby on the Ordnance Survey, and became sole agent of the OS in 1823. He was a founding member of the Royal Geographic Society.