The word "战役" is formed conceptually by combining two characters that each contribute a layer of military scope. "战" (zhàn) represents the core idea of fighting or a single battle. It is then compounded with "役" (yì), which carries the meaning of a campaign, service, or a designated military operation involving multiple engagements. Therefore, the formation merges the notion of combat ("战") with the broader framework of a coordinated, strategic operation ("役"), effectively creating a term that signifies a major military campaign comprising a series of connected battles toward a common objective.