Prat was promoted to a lieutenant on September 9. The future hero returned to Naval School, but this time as an instructor. From 1871, he was the Second Commander of "Esmeralda", leading to his appointment to several positions in the school (teacher, subdirector, internal director), and was assigned to teach courses such as Naval Order, Law, Naval Tactics and Cosmography. Additionally, he was responsible for docking the corvette for four years (1871–1874) in the port of Mejillones. He received the title of Graduated Corvette Captain (equivalent to lieutenant commander) in 1873 and in 1874. He was a dedicated teacher who fought against the lack of resources available to provide quality education. He himself translated textbooks from French to Spanish.