during the war; wartime
Refers to the period while a war is ongoing. Often used in historical or narrative contexts.
During the war, many people suffered from food shortages.
During the war, goods were rationed.
戦時中 and 戦時下 both mean 'during the war', but 戦時中 is the everyday spoken term while 戦時下 is more formal and typically appears in historical or written contexts.
Compound of 戦時 (senji, 'wartime') + 中 (chū, 'during').