The stage was set for war. Literally. Inside a small Tuscan theater with a mock-up of a World War I trench, Susanna Ceccardi, a rising star of Italy’s hard-right League party, was flanked by rival candidates for the European Parliament elections and firing angry salvos against a club she soon hopes to join. a person standing in a room: Graffiti in Brussels, where the European Commission and European Council meet. “This Europe must be changed, this Europe of bureaucrats, do-gooders, bankers, boats of migrants, it has to be changed,” Ms. Ceccardi, the 32-year-old mayor of Cascina, Italy, roared to smatters...