What is grammatically correct had ceased or ceased?

Answer 1

Both are correct in proper context. The preterite indicates an action in the past: "The fighting ceased." The pluperfect indicates action prior to a main verb in the past: "It was quiet because the fighting had ceased."

Answer 2

Both "had ceased" and "ceased" are grammatically correct, but they are used in different contexts. "Had ceased" is used in the past perfect tense to indicate an action that was completed before another past action. "Ceased" is used in the simple past tense to indicate that something came to an end.