After the Badoglio Proclamation of 8 September 1943, Roberto Lucifero d'Aprigliano participated in the Roman resistance against the city's occupation by German forces, as a member of an underground monarchist group.

As a member of the PDI party executive, he took on responsibility for contributing to the daily news publication "monarchico Italia nuova", from the pages of which he attacked the antifascist measures of the Bonomi government and the "dictatorship" of the National Liberation Committee ("Comitato di Liberazione Nazionale" / CLN).

[1] Lucifero d'Aprigliano used "monarchico Italia nuova" to promote his opposition to the very broad political coalition underpinning the CLN, which was at variance with the mood of the times.

In the Constituent Assembly Lucifero d'Aprigliano intervened on matters such as the "right to strike", regional autonomy, church-state relations, the preservation of public morality and the use by the old aristocracy of their titles.

The lead he had taken led to Lucifero d'Aprigliano being elected national secretary of the Italian Liberal Party ("Partito Liberale Italiano" / PLI).

His continuing fervent monarchism remained out of tune with the political mainstream and his incumbency as party secretary turned out to be brief, lasting from December 1947 till October 1948.