民國肇建十餘年間，軍閥派系對立，國家十易「元首」，兩度出現帝制，32次更換內閣，造成國家極度混亂局面。國父孫中山先生痛心國家分裂，使革命大業頻遭挫折，因而創立黃埔軍校，國民革命軍建軍的歷史，肇始於斯。 黃埔軍校的成立，最重要的影響即為：第一，奠定了廣州革命基地，成為日後北伐成功的主要武力；第二，國父孫中山先生逝世後，蔣中正校長成為其革命事業的繼承者，而國民革命軍的編成，代表國民政府軍事力量的統合，亦為軍隊國家化的起步。 革命軍在面對戰力優勢之敵，以「打倒吳佩孚」、「聯絡孫傳芳」、「不理張作霖」的構想，以各個擊破戰略，而能迅速擊滅吳佩孚，戡定湘、鄂；繼擊滅孫傳芳，底定東南，收復南京；最後奪取魯南，分進合擊會師平津，在兩年三個月內打破歷史上的成例，完成了中國的統一。

After Republic of China (R.O.C) established in 1912, during the time more than ten years due to warlords and sectarians against each other it has caused extremely chaos situation, such as changing the President 10 times, adopting emperor system 2 times and reshuffing cabinet 32 times. Sun Yat-Sen, R.O.C. Founding father, worried that the state division might undermine the achievement of domestic revolution. Therefore, he created the Whampoa Military Academy in 1924, and the military history of National Revolutionary Army (N.R.A.) has begun accordingly. The most important influence of Whampoa was to setup Guangzhou as the base of revolution and the major force of N.R.A. for the Northern Expedition. Secondly, when Sun passed away, Chiang Kai-shek, as Sun's successor, carried on not only the integration of armed forces but also the initiative of nationalization. N.R.A. adopted｀Divide and Conquer´strategy. This concept was composed of｀break down Wo Pei-fu´,｀contact Sun Chuan-fang´and｀ignore Chang Tso-lin´, especially whenenemy forces was superior to them. Furthermore, it could defeat Wo quickly, and also settle down Hunan and Hubei provinces. Afterwards, N.R.A. could destroy Sun and take back the capital of Nanjing. Finally, Shandong province could be seized and Peking and Tianjin could be recovered from a different direction. In term of time, it only spent two years and three months in reunification and set a new record in China's history.