Why was Israel able to seize so much territory during the Six Day War?

Answer 1

There are three major reasons why Israel was able to capture so much territory from its adversaries in the Six Day War:

Israeli Preparation: Israelis realized that if Israel were to lose any conflict with the Arab States, Israel would cease to exist as an independent state. Therefore, Israeli generals and leaders spent years pouring over plans to defend the State and what methods of attack could most effectively quell the opposition. Israeli leaders had detailed topological surveys of the Sinai Peninsula and the Golan Heights which were used when taking those territories. By contrast, Arab political leaders and generals spent much more time saber-rattling and declaring that they were going to destroy Israel without forming any plan to actually achieve that.

Surprise Attack: Although Egypt and Syria were definitely preparing to attack Israel and had made overtly hostile moves, Israel's first move of carpet-bombing the entire Egyptian Air Force took the Arabs by surprise. This swift move guaranteed Israel air superiority and made the Israeli tank and infantry divisions freer to move. This in turn led to more forceful advances. The Arabs did not recover from the advantage Israel had acquired from being the first-mover.

Incompetent Arab Generals: In the Sinai Peninsula, particularly, there were hugely conflicting reports about Arab losses and confusion. As a result, the Egyptian command ordered the tank divisions to withdraw without a clear method of retreat. Many in the Egyptian tank-core believed that they were denied a proper engagement with Israel, which they may have been able to win. Instead, they formed an easy-to-target-from-the-air column of tanks moving slowly to avoid getting stuck in the sand. In this way, Israel was able to compel an Egyptian evacuation from the Sinai Peninsula with only a third the number of tanks that the Egyptians had.