Don Jose Maria Cabrer was born in 1761, the son of a military engineer. His father trained him in his profession and the young Cabrer set out to fight the British in Jamaica as part of Spain’s involvement in the American Revolution. However, en route he was rerouted to Río de la Plata, where he was ordered to serve in the commission then starting to demarcate the border as set out by the Treaty of Ildefonso.
This first commission was organized at the request of Charles III, who wanted to avoid the ambiguity that had led to previous conflict over the border. The new border was split into five sections, with Diego de Alvear y Ponce de León, a naval officer and founder of a dynasty of Argentine politicians, in charge of the section near the Paraná and Paraguay rivers. Cabrer worked under Alvear, who is mentioned in the title of this map along with other officials who directed the surveying project. Alvear eventually promoted Cabrer to the position of Second Commissioner and Geographer of the works and ordered Cabrer to survey and explore the river Pepirí Guazú, part of the second division of the surveying work that still needed to be done.
Cabrer finally returned to Buenos Aires in 1801, where he learned of the deaths of many of his family members back in Spain and decided to stay in Buenos Aires for the duration of his life. Despite compiling decades of work into this map, it was not published at the time. Instead it seems Cabrer kept it, which is how it came to play a role in the contentious politics of Argentina in the mid-nineteenth century.
Cabrer was still in Buenos Aires and in 1831 he was appointed to the Topographic Department; he died in 1836.