 After the Armistice with Italy of 8 September 1943, aged 21, Marcora entered the Italian resistance movement, with the nickname of Albertino, fighting in the province of Milan and the Ossola, and participating in the liberation of Milan on 25 April 1945.He was one of the founders of the Christian Democracy (Democrazia Cristiana).He later was appointed as party's provincial secretary of Milan and vice-secretary national.