The appeal, 〈Cheong Kwon-seol Min-bo Zeung-su Kang-bang So(請勸設民堡增修江防疏)〉 was written by Kang Wi, a well-known reformer and early proponent of enlightenment thought. However, despite its obvious importance, academic circles have so far largely ignored this document. Moreover, the period in which this document was written has been wrongly assumed as being after the foreign disturbance of 1866. This paper undertakes a study of the 〈Kang-bang So〉 with the objectives of uncovering the actual time period in which it was formulated and of identifying the reasons why Kang Wi became a member of the progressives. A statement found in the 〈Bon-jeon(本傳)〉 written by Lee Joong-Ha, which states that, this foreign disturbance occurred in the capital region in 1866, has so far been the main reason why scholars believe that the 〈Kang-bang So〉 was actually written after the foreign disturbance of 1866. While this statement is clearly in reference to what has come to be known as the first foreign disturbance, in which a French fleet attacked Chosun in 1866, the fact that the 〈Kang-bang So〉 was clearly written after this incident is evidenced by the following: First, an identical appeal was recorded in the 《Sin Heon Collections(申櫶全集)》, where it was given the name of 〈Non Byeong-sa So(論兵事疎)>. The following statement is included at the end of this document, disturbance at the end of August 1866. Second, there are no references to the French attack of 1866 within the 〈Kang-bang So〉 itself. On the other hand, the 〈Kang-bang So〉 makes reference to China's experiences with foreign disturbances when laying out his plan for a proper defense, thus implying that Chosun had yet to encounter any real foreign threat. This paper argues that the 〈Kang-bang So〉 was actually prepared in response to an incursion by two Western fleets into the Yanghwajin area of the Han River on August 18th, 1866: an incursion which led King Kojong to order that defense measures be established immediately. As a result Kang Wi was asked by military commander Shin Heon to analyze the condition of the rivers flowing from Kang-hwa Island to Yang-hwa Jin: which in turn led to Kang"s submission of the 〈Kang-bang So〉, a document that listed the defensive measures that should be taken in order to fend off a Western invasion. The 〈Kang-bang So〉 is a defensive strategy that combines the strategies found in the 〈Ju-hae(籌海)〉 section of the book 《Hae-kuk-do-ji(海國圖志)》, which was written by Wi Won, with the national defense theory introduced by Chong Yak-Yong in the 《Min-bo-eui(民堡議)》. Chong Yak-Yong s national defense strategy, which was still relevant in the middle of the 19th century, first emerged as a means of countering the weaknesses of the defense forces caused by the rampant corruption of the Army Administrative System. However, Chong Yak-Yong"s defense strategy was not effective against Western invasions, or against attacks by Japanese marauders. As such, Kang Wi"s strategy was to mobilize the common people to assure national defense, thus protecting the kingdom and solving the nation's acute shortage of soldiers in one stroke. As mentioned above, Kang Wi adopted a detailed defense strategy that was largely based on the 〈Ju-hae〉 section of the 《Hae-kuk-do-ji》. Kang introduced a defense strategy to protect the rivers against Western invasions that was based on the Sa-nae-ha(守內河) concept found in the euisu(議守) chapter of the 〈Ju-hae〉. The main difference between the strategies adopted by Kang Wi and Wi Won was that while the latter emphasized using local militaries, Kang Wi advocated the use of national defense forces composed of commoners. As such, given the reality of Chosun"s situation, Kang Wi intended to complete the Su-nae-ha strategy found in the〈Ju-hae〉 by combining it with the national defense theory created by Chong Yak-Yong.Two other individuals, Yun Seop and Park Ju-Woon, also formulated strategies to fend off Western invasions. Their strategies were based on the traditional Korean defense strategy known as the Geo-heom Cheong-ya(據險淸野). Meanwhile, Kang Wi s strategy was based on changing the traditional defense strategy to respond to the growing specter of Western invasion. Kang expected that his strategy would be successful in defending against any potential Western invasion. However, it is difficult to see how the country could have been defended against a Western power sporting modernized weapons simply by changing the nation s defense strategy without introducing any new weapons. Having experienced the first two recorded foreign disturbances of 1866 and 1871, Kang Wi eventually realized that his strategy was ill-equipped to deal with the Western powers. Kang became very critical of these illogical defense measures and of the Taewongun"s isolation policy after the two encounters with Western fleets. Kang abandoned his belief that Chosun could stem off any Western invasion and even defeat the Western fleets using traditional defense strategies. Rather, Kang Wi decided to develop a better understanding of the Western powers, a process which led him to join the progressive camp after the two trips he took to China in 1873 and 1874.