Final answer:
In Lord Byron's Gothic poem 'Manfred,' the character Manfred goes out to summon the spirits at midnight, a time often associated with supernatural occurrences in Gothic literature.
Step-by-step explanation:
The Gothic time Manfred chooses to summon the spirits in the dramatic poem “Manfred” by Lord Byron is midnight. This choice emphasizes the mysterious and eerie atmosphere typical of Gothic literature. Midnight has been depicted often in horror novels and films as a time when supernatural activities reach their peak, matching the behavior of legendary creatures such as vampires, who are known to cause mischief at this hour before retreating by dawn.