How did Israel win the Six-Day War?

Question

Considering Israel fought several Arab countries, which had troops largely outnumbering the Israeli, how did they manage to win the war decisively, with much fewer casualties than the Arab countries?

The Wikipedia page also lists Israel is the the only belligerent on their side (ie: they had no allies), is this true? Did Israel fight the war with no American support?

Answer 1

If you look only at the numbers, then Israel was bound to lose the war of course. The Arab countries had far more soldiers and they also had better/more equipment (the Soviet Union supplied them well). This view leaves out a number of important factors however:

• Surprise: By launching a preemptive attack Israel took the Arab countries by surprise which allowed taking out their air forces on the ground. Even the most powerful air force isn't worth anything if it doesn't leave the ground. This certainly helped even though Israel managed to win other wars without having any such advantage (see 1948 Arab–Israeli War and Yom Kippur War).
• Motivation: The IDF (Israel Defense Forces) was highly motivated - a failure would inevitably mean that Israel would cease to exist. Arab countries on the other hand had to take measures to keep their soldiers from defecting (Syrian forces even had to chain their soldiers to machine guns it seems).
• Skill: The Israeli soldiers were highly skilled, with one of the reasons being the overall high education level in the population. This was probably the main disadvantage of the Arab armies - while they got all the advanced weapons from the Soviets, their soldiers were unable to use them effectively.
• Organization: The Arab countries didn't coordinate their actions, each of their armies was acting on their own. In fact, Egypt even failed to coordinate its own troops.

As to whether Israel had allies in this war: no. While the USA always supported Israel they did it mostly by diplomatic means. And they supplied Israel with weapons (it was Cold War - if the Soviets supply the Arabs then USA has to supply Israel). But nothing beyond that. The newspaper I linked to above says that this result "would have been unthinkable but not for gross Arab incompetence" - and I think that this is correct.

In fact, Egypt claimed that Israel received military help from USA and Great Britain. As Wikipedia notes, these claims haven't been taken too seriously outside the Arab world. The death blow to the accusation was an intercepted phone conversation between Nasser and King Husein that Israel released to the press:

Nasser: ...Shall we include also the United States? Do you know of this, shall we announce that the U.S. is cooperating with Israel?
...
Nasser: Hello, will we say the U.S. and England or just the U.S.?
Hussein: The U.S. and England.

Answer 2

The Egyptians, along with Syria and Jordan, had worked up a plan to attack Israel a couple of weeks prior to the actual war. Apparently some recently declassified documents confirm that the Egyptians had planned to launch bombers against Israel to take out their airfields and other strategic military positions. They had also deployed a number of tank units that were prepared to slice through the country.

The Israelis were trying to convince Lyndon Johnson to provide support, but the US was already involved with VietNam and wasn't prepared to provide any type of military assistance in defending Israel. However. the Israelis did convince him that an attack was imminent. As a result, Johnson warned Egypt not to attack and informed the Soviet Union that if Egypt did attack, the US would hold the Russians accountable. The combined pressure from the US and Russia proved to be enough to convince Egypt to postpone their attack.

About a week later, Israel decided that the Arab countries were not going to delay much longer, so they chose to take the offensive. The Israeli air force wiped out the Egyptian and Syrian air forces while they were still on the ground, and therefore had no resistance at all in the air. Two days later the Israelis destroyed almost all of the Egyptian tanks, thereby eliminating the last opportunity the Arab countries had to mount any form of attack.

Basically, the Israelis took the initiative away from Egypt and then turned it around and did exactly what the Egyptians were planning to do to Israel. The only form of assistance that Israel received was the political intervention leading up to the actual event, and that proved to be enough.