In 1789, after the death of his patron, Archbishop Gaspar de Bragança, Amarante began a military career. In 1792, he was appointed second lieutenant of the Royal Corps of Engineers and was tasked with drawing a topographical map from the Serra de Rio Maior to
Leiria. He was promoted to first lieutenant in 1796 and, from 1799, was responsible for overseeing the construction of roads and bridges across Portugal. It was a
pontoon bridge comprising 20 boats connected by iron ties, which could be opened to allow ships to pass through. This was the site of the
Porto Boat Bridge disaster when the bridge partially collapsed as thousands of Porto residents fled invading French troops during the
First Battle of Porto. In a prior plan from 1802, he had designed a single-arch stone bridge for the location, but the pontoon bridge design was chosen instead. == Death and legacy ==