This sentence means that truth is often the first to be sacrificed in war. War often leads to confusion and misleading information, making it difficult for people to determine the truth. In order to achieve their own goals, all parties may create lies, exaggerate facts, distort the truth and other means to cover up their true intentions or actions. In addition, there may be information blockade, deliberate misleading and false reports in the war, which makes it difficult for people to understand the real situation of the war. Therefore, in war, truth is often the first to be sacrificed.