CORTE, France — The sea of white-and-black Moor’s-head flags rose against a soundtrack of plangent Corsican pop and the auditorium was suddenly transformed. An election-eve political rally had become an emotional family gathering where all were in agreement.

Speaker after speaker rose to proclaim what the crowd already believed: Corsica’s nationalists would win big in territorial elections on Sunday, they were unstoppable, and the mainland had better take notice.

If Corsica’s nationalists have their way, this rugged, cantankerous island that for centuries has been going its own way would become Europe’s next big secessionist tug of war, alongside Spain’s dispute with Catalonia, or Britain’s with Scotland.

But whether or not the French government is ignoring the Corsican movement at its own peril, the reaction from Paris has been virtually uniform: Nothing.