關於蔣中正於中日戰爭初期的戰略，學界常突顯外交運作或是淞滬會戰的地位；相對而言，平津失陷後的華北並未受到如此高的關注。之所以如此，或是因淞滬會戰最終演變為戰爭期間最大規模會戰，吸引世界目光，對全局走向並有關鍵影響。然而，淞滬會戰固然重要，華北作為日軍首先匯聚兵力之處，且為戰爭初期與淞滬平行之主戰場，亦有其重要性。本文從蔣中正的華北戰略切入，考察其戰前、戰爭初期針對華北的整體軍事布局，復聚焦於「空間換取時間」內涵與實踐的探討，俾重新認識這場戰爭的開端。

Regarding Chiang Kai-shek’s strategy in the early days of the Sino-Japanese War, scholars have often highlighted either the status of diplomatic operations or the Battle of Shanghai; relatively speaking, the warfare in North China after the fall of Beiping-Tianjin have not received such high attention. This may be due to the fact that the Battle of Shanghai led to the retreat of the Nationalist Government from its power base on the Lower Yangzi and forced it to reshape its wartime geopolitics later. Despite the significance of this battle, the Incident of Marco Polo Bridge in Beiping triggered the military conflicts between China and Japan, and North China was the battlefield parallel to Shanghai. Through an analysis of Chiang Kai-shek’s strategy and his overall military layout for North China before and right after the outbreak of the war, this article discusses the connotation and practice of the so-called “trade space for time” and offers a new understanding of how Chiang developed the war plan in the early stage of the war.