brigades and four armoured groups. Later, the army fought in the North Yemen Civil War from 1962 to 1967, and the 1967 Six-Day War. North Yemen Civil War Within three months of sending troops to Yemen in 1962, Nasser realized that the engagement would require a larger commitment than anticipated. By early 1963, he would begin a four-year campaign to extricate Egyptian forces from Yemen, using an unsuccessful face-saving mechanism, only to find himself committing more troops. A little less than 5,000 troops were sent in October 1962. Two months later, Egypt had 15,000 regular troops deployed. By late 1963, the number was increased to 36,000; and in late 1964, the number rose to 50,000 Egyptian troops in Yemen. Late 1965 represented the high-water mark of Egyptian troop commitment in Yemen at 55,000 troops, which were broken into 13 infantry regiments of one artillery division, one tank division from the Egyptian Armoured Corps and several Special Forces as well as airborne regiments (Aboul-Enein, p21). All the Egyptian field commanders complained of a total lack of topographical maps causing a real problem in the first months of the war. 1967 War Before the June 1967 War, the army divided its personnel into four regional commands (Suez, Sinai, Nile Delta, and Nile Valley up to the Sudan). The remainder of Egypt's territory, over 75%, was the sole responsibility of the Frontier Corps (Egypt). In May 1967, Nasser closed the Straits of Tiran to passage of Israeli ships. On 26 May Nasser declared, "The battle will be a general one and our basic objective will be to destroy Israel". Israel considered the closure of the Straits of Tiran a casus belli. The Egyptian army then comprised two armoured and five infantry divisions, all deployed in the Sinai. In the weeks before the Six-Day War began, Egypt made several significant army organisational changes. Field Marshal Amer created a new command interposed between the general staff and the Eastern Military District commander, Lieutenant General Salah ad-Din Muhsin. This new Sinai Front Command was placed under General Abdel Mohsin Murtagi, who had returned from Yemen in May 1967. Six of the seven divisions in the Sinai (with the exception of the 20th Infantry 'Palestinian' Division) had their commanders and chiefs of staff replaced. What fragmentary information is available suggests to authors such as Pollack that Amer was trying to improve the competence of the force, replacing