His power in the town of Cajamarca and the surrounding area was that of a feudal magnate, and he had been recruiting troops with his own money—effectively a private army—since the war with Spain in 1866.

He had been one of the senior army officers present at the Peruvian victory on the "Dos de Mayo," was given the rank of Colonel, and was named Prefect of Cajamarca.

In 1874, Iglesias initiated a revolution against the government of President Manuel Pardo and proclaimed himself the political and military Chief of the North.

When war broke out in 1879 between a coalition of Peru allied with Bolivia and Chile, Iglesias commenced raising a new private militia.

Subsequently, Iglesias's friend, Nicolás de Piérola, launched a successful coup d'état, declaring himself Supreme Commander in Chief.

Because the professional Peruvian army had previously been decimated in the south, losing much of its most modern equipment, Iglesias had only primitive, Peruvian-manufactured rifles without adequate sights and inferior to the Chilean Krupps.

Having escaped back to Cajamarca, Iglesias continued the war against Chile in the north of Peru, while General Andrés Avelino Cáceres fought against the Chileans in the Andes.

On 27 August 1884, guerrilla fighters launched an armed assault against Lima and almost managed to fight their way into the presidential palace, but were repulsed.

Iglesias and his wife had eleven children, and 1895 was also the year that the General's youngest daughter, Gaudencia, married a Scot named Edgar Fraser Luckie, who had made a fortune from gold mining in British Guiana and then bought the Andalusia sugar farming estate near Sayan, north of Lima.