Pritz was part of the First Division, also called División Bloqueo, of the Brazilian navy operating in the waters of the Rio de la Plata during the Cisplatine War. The mission of this squadron, initially commanded by James Norton but eventually taken over by Pritz, was to blockade the primary Argentine port of Buenos Aires. Although the squadron had superior resources compared to the Argentine navy, commanded by William Brown, it was unable to stop the Argentines from routinely escaping.