In 1915 Enrico Mizzi was elected member of the Comitato Patriottico Maltese and founded the newspaper L'Eco di Malta, organ of the Committee itself.

While Mizzi was striving to obtain a liberal Constitution he was arrested at his residence on 7 Mayand court-martialled on charges of sedition in 1917 under the Malta Defence Regulations for writings and statements against the British.

The sentence was commuted by Governor Methuen to a "severe censure", while his civil rights and warrant were restored following the cessation of hostilities in 1918.

[7]After the end of the First World War, Mizzi was part of the large and moderate coalition called the Maltese Political Union (Unjoni Politika Maltija, UPM), led by Ugo Pasquale Mifsud.

It splintered from it, together with the more extremist and pro-Italian current, to form the Democratic Nationalist Party (Partit Demokratiku Nazzjonalista, PDN), led by Mizzi.

[9] On 23 January 1926 the two parties joined together to form the Partit Nazzjonalista, with Mizzi acting as a co-leader together with Sir Ugo Mifsud till the death of the latter in 1942.

[citation needed] In the years from 1924 to 1933 Mizzi held numerous ministerial positions and was president of the Dante Alighieri Society and director of the Gazzetta maltese in his capacity as a promoter of the Italian character of Malta.

Between 1939 and 1942, the Times of Malta and Il-Berqa, two newspapers owned by Gerald Strickland, called him a quisling and a sympathiser of Italian Fascism.

[16] At the 1950 elections the Partit Nazzjonalista reported a great success and Mizzi was appointed Prime Minister in a hung parliament.