Antonyms:
* Ceasefire: To stop fighting or hostilities.
* Truce: A temporary suspension of hostilities.
* Peace: A state of tranquility and harmony.
* Inaction: Lack of activity or movement.
* Withdrawal: To retreat or pull back from a situation.
Synonyms:
* Drive: A focused and organized effort.
* Crusade: A vigorous and sustained campaign for a cause.
* Push: A strong effort to achieve something.
* Effort: A strenuous attempt.
* Operation: A planned and organized activity.
* Movement: A group of people working together to achieve a goal.
* Promotion: A planned activity to increase awareness or sales.
The best synonym or antonym will depend on the context of how "campaign" is being used.