江戶時代懷德堂學派的代表人物五井蘭洲在其軍事著作『兵論』中, 通過以孔孟的“臨事而懼、好謀而成”與“人和”爲“兵要”, 將兵學歸攝於儒學體系之中, 並強調文武一途, 不可偏廢。在用兵方法上, 五井蘭洲崇尚智謀, 認爲戰前的廟算是戰爭勝負的決定性因素;主張認清廟算、機變、人和才是用兵之本, 而佈陣、兵械不過是用兵之末, 不可捨本逐末。在用兵倫理上, 他堅持義謀並重, 反對只著眼於正義性而忽視可行性的作法, 甚至認爲只要是爲了達成正義的戰略目標, 也可以使用詭詐的戰術手段。雖然五井蘭洲以朱子學傳人自居, 但其“儒表兵裡”的軍事觀以結果爲導向, 努力抬高智謀的地位而淡化道義的色彩, 嚴重偏離了朱子學“以義爲先”的原則, 具有鮮明的江戶時代特色。
Goi Ransyuu is the representative personage in Kaitokudou School. In his On Military, he treated Confucius’s saying “proceeding to action full of solicitude, adjusting plans and carrying them into execution” and Mencius’s saying “unity of the people” as the key of military, incorporating military science into the system of Confucianism, and insisting the uniformity of pen and sword, neither of which could be neglected. In regard to military methods, Goi Ransyuu advocated resourcefulness, and considered court calculation prior to war as the decisive factor in winning a war. In his opinion, recognizing court calculation prior to war, flexibility in dealing with exceptional situations, unity of the people are fundamental, while military array and weaponry are trivial, and it’s wrong to attend to the trivials and neglect the fundamentals. As to military ethics, he laid equal stress on morality and resourcefulness, objecting to one-sidely stress on morality and neglect feasibility. He even agreed with achieving a justicial strategic goal by cunning tactical means. Although Goi Ransyuu consider himself as a follower of the doctrines of Zhu Xi, he underlined the importance of resourcefulness and downplayed the importance of morality, which deviates the moral principle of Zhu Xi. With Confucianism in appearance while Military Strategist in nature, his result-oriented view of military is of distinguishing Edo Era characteristics.