Complex sentence: The retreating Swiss army seized the upper-Lombardy province of Ticino to cover their retreat, leaving a rearguard to preside it, later it was incorporated in the Swiss Confederation as the Canton Ticino, remaining to this day an Italian-speaking enclave in Switzerland.
Split into simpler sentences: The retreating Swiss army seized the upper-Lombardy province of Ticino to cover their retreat, leaving a rearguard to preside over it. Later it was incorporated in the Swiss Confederation as the Canton Ticino, remaining to this day an Italian-speaking enclave in Switzerland.