I can speak for the outcome of the 1967 war, or the Six Days War. The stunning Israeli victory over the combined forces of Egypt, Syria and Jordan can be boiled down to three main factors; Israel's successful surprise attack on the Egyptian air force on the first day, the incompetence of the Egyptian officer corps, and a lack of coordination between the various Arab governments.

First of all, the Israeli military leadership recognized the vital need for air superiority in order to provide cover for its ground forces against Arab positions. Thus, the primary objective of Israel's pre-emptive strike was to destroy the large Egyptian air force on the ground, ensuring their mastery of the skies for the duration of the conflict. Early in the morning of June 5th, almost all of Israel's air force flew low over the Sinai coast to avoid Egyptian radar, followed by a massive bombing campaign of Egyptian air bases. The success of the attack surprised even the Israelis, with most of Egypt's planes never even making it off the runway. With the Egyptians devastated and a lack of any significant air power from Jordan or Syria (the latter in part due to political purges), the Israelis were able to bomb Arab positions throughout the remainder of the war without the threat of enemy aircraft, which was vital to their success in Sinai, the West Bank, and the Golan Heights.

Second, while moral among the Egyptian soldiers was high in the build up to hostilities, the military leadership of the most powerful Arab state was seriously weakened. Nasser's Chief of Staff of the Egyptian army, Abdel Hakim Amer, had been granted control of the armed forces due to his personal friendship with Nasser and his political loyalty. To cement his personal control of the army, Amer had appointed men loyal to him to positions in the officer corps, rather than men of competence. It did not help that at the same time as the Six Day War commenced, many of Egypt's best troops and officers were bogged down in a brutal stalemate in Yemen, supporting Arab nationalists against the monarchial government. Thus, at the opening of the conflict with Israel, Egypt's military leadership was severely compromised, not to mention lacking sufficient training to make use of its Soviet provided planes. Still, the Egyptians might have been able to stall the Israeli advance into Sinai using the three lines of fortifications that had been constructed for just such a need; however, on hearing of the Israeli advance, Amer panicked and ordered a massive, disorganized retreat from Sinai, effectively abandoning the peninsula to the Israelis.

Finally, a lack of effective coordination between the governments of Egypt, Syria and Jordan further undermined the Arab cause. The three nations had been politically hostile in the years, even weeks before the war, especially so between Jordan and Egypt. Jordan in fact only committed itself to an alliance with Egypt in the week before the start of the war. Throughout the conflict, deception and lack of coordination hampered the Arab war effort. Nasser urged King Hussein of Jordan to attack Israel from the West Bank after the destruction of the Egyptian air force; he claimed that the Egyptians were advancing on Tel Aviv and that the aircraft Jordanian radar had picked up over Sinai were Egyptian, not Israeli. Thus misled, Jordan attacked, not learning until later that the Egyptian claims, being broadcast over Cairo's "Voice of the Arabs" radio, were all a hoax. At the same time, Syrian troops shelled Galilee from atop the Jordan heights, but did not conduct any offensive into northern Israel, thus leaving the Israelis free to commit the bulk of their forces against Egypt and then Jordan. Once the latter were defeated, Israel was free to attack the Golan Heights, and many of the Syrian officers there, as in Egypt chosen for political reasons rather than competence, abandoned their men and fled.

Thus, a combination of Israeli air superiority from preemptive strike, incompetence among the Arab officer corps, and failure to coordinate between the governments were the main factors in Israel's victory in the 1967 war.