Upon his return to Peru in 1874, he devoted himself to the management of one of the family plantations in the Tambo Valley and worked in the fledgling agricultural development and engineering circles of the country.

When the war with Chile broke out in 1879, he was appointed commanding general of the civic division of Tambo which operated in the coast of Arequipa.

Having under his command three battalions, he took an active part in the expedition which stopped the Chilean Army from entering Arequipa city and compelled it to reembark at Mollendo.

Residing in Arequipa after the war, he was elected President of the Liberal Club and served three terms as Director of the Public Charity of the city.

The following year he was elected Mayor of Arequipa but was compelled to resign due to a conflict of interest with the city's infrastructure projects.

By July 1899, when Piérola's administration called general election, the National Coalition offered the presidential candidacy to his brother Alejandro (former Prime Minister) but he declined in favor of Eduardo, an independent.

López de Romaña reshuffled his cabinet almost exclusively with civilistas, a move which resulted in the majority democrats of the Chamber of Deputies to continuously censure.