Complex sentence: The nuns assumed that "Expedite" was the name of a martyr, prayed for his intercession, and when their prayers were answered, veneration spread rapidly through France and on to other Roman Catholic countries.
Split into simpler sentences: The nuns assumed that "Expedite" was the name of a martyr, and prayed for his intercession. When their prayers were answered, veneration spread rapidly through France and on to other Roman Catholic countries.