Complex sentence: By order of Belgrano, and to protect their backs, he left the town with all its silver and he attempted to destroy Potosí's mint; but a warning of an officer to the populace averted the destruction.
Split into simpler sentences: By order of Belgrano, and to protect their rear, he evacuated the city, taking with him all of its silver. He also attempted to destroy Potosí's mint; but a warning of an officer to the populace averted the destruction.