In 1820, during a stay on the western coast of South America, Brommy enlisted as a midshipman in the Chilean Navy, at the time when it was led by British nobleman Lord Cochrane, the former Royal Navy officer who had achieved distinction in the Napoleonic Wars. Cochrane undertook the education of young Brommy, so that the youth was soon fit to take on his first command: the 18-gun brigantine "Maypo". Brommy took part in several actions in Chile's War of Independence against the Spanish including the capture of Valdivia. When Brazil became an independent empire in 1822, Cochrane left Chile in order to develop a Brazilian fleet. Brommy followed him, remaining in Brazilian service until 1825.