JERUSALEM (JTA) Nearly a year has passed since Israel’s 2006 war in Lebanon, and 40 since the June 1967 war.Those familiar with last summer’s war might well rub their eyes in disbelief. Given how badly the Israel Defense Forces performed in Lebanon, where it was stymied by a guerrilla organization numbering just a few thousand fighters, is it really true that once upon a time the IDF routed four Arab armies in just six days?Indeed it did. There was a time when the Israeli people, to quote Moshe Dayan, was “small but brave.” The IDF was the only thing keeping Israel from death at the hands of its much larger and supposedly more powerful neighbors. The outcome of the 1967 war was a feeling of “ein brera” – no choice – that used to permeate all layers of Israeli society, resulting in extremely high motivation. That motivation meant the IDF was able to attract the country’s best manpower. Though pay was meager and conditions often difficult, people were eager to serve in the IDF, and did so proudly.That motivation made possible training, selection and promotion procedures that were, or at least were widely perceived as, just and fair. The final outcome was the creation of a general staff made up of men – no women yet – who were clear-headed and determined to win even at a high cost in casualties.The ever-present fear of the future generated national unity, and national unity generated truly tremendous fighting power. In June 1967 the IDF may not have possessed the world’s best doctrine or weapons. The former lagged behind the times and did not yet fully embrace the concept of combined arms that other armies had developed. Some of the latter – including many tanks, fighting vehicles and artillery pieces, communication equipment and even small arms – dated to World War II.Of the three services, the worst equipped was the Navy. Not one of its vessels was modern. It did not even have a radar apparatus of its own, a fact that probably contributed to the mistaken attack during the war on the USS Liberty. Only the Air Force, with its French-built Mirage III fighters, was up to date. However, the Mirages formed only about half the stock of warplanes, much of which was also antiquated.Relying on surprise and taking a tremendous risk by leaving the homeland almost without air cover, Israel opened the war on June 5, 1967 with a devastating air attack on the Egyptian, Syrian and Jordanian air forces. All three enemy air forces essentially were knocked out within a few hours.Israel’s small size and the fact that it was positioned between its main enemies meant it was operating on internal lines. Making full use of them, the IDF shifted formations from one front to another, probably increasing the available forces by 25-30 percent. The IDF launched a classic Blitzkrieg campaign: The enemy’s defenses were smashed, its rear penetrated, its forces surrounded and annihilated. All this was achieved in the war’s first three days and at a relatively low cost of fewer than 800 troops killed. The best-known military critic of the time was an Englishman, Basil Liddell Hart. In an article he wrote for the now defunct journal Encounter, Hart claimed that the Israeli operations represented “a superb application of the strategy of indirect approach” – by which he meant going around the enemy’s main stronghold – that he had championed for decades. But there was nothing subtle about the Israeli tactics. At Rafa in the northeastern Sinai, at Ammunition Hill north of Jerusalem and along the handful of difficult roads leading up the Golan Heights, the Israelis attacked head-on. Elsewhere, particularly along the southern part of the frontier with Egypt, things were a little more complicated, but the outcome was always a decisive Israeli victory.As usual, the fog of war prevailed and there was much chaos on the battlefield. Entire brigades got lost, while other units ran out of fuel and had to improvise.No matter: Making up for those problems the Israelis, regulars and reservists, fought like demons. In the words of the Prophet Joel: “Their faces gathered blackness; they ran like mighty men; they climbed the walls and did not break rank; the earth quaked before them; and the Lord made His voice heard in front of His army.”The 1967 war gave Israel what it considered “defensible borders,” but it did not lead to security, let alone peace. Less than two years after the war ended, in March1969, massive fighting known as the War of Attrition broke out along the Suez Canal; it lasted until the summer of 1970. Then came the October 1973 Yom Kippur War, then the 1982 invasion of Lebanon, then the first and second Palestinian intifadas. In 1973 the IDF fought as well as in 1967, if not better. Since then, however, its performance has steadily deteriorated. Forty years after June 1967, the point remains that an army is only as good as its opponent. A force that beginning with the 1982 invasion of Lebanon has fought only opponents much weaker than itself has become weak; a sword, thrust into salt water, will rust. If the 2006 war in Lebanon proved anything, it was just how rusty Israel’s “Swift, Terrible Sword” – the title of one of the countless books written about the 1967 war – has become. It also proved that as long as the Israelis go on fighting the weak, they risk leaving themselves unprepared to resist the strong who may still come at them. Martin van Creveld, of Jerusalem, is one of the world’s leading experts on military history and strategy. He is the author most recently of “The Changing Face of War” (Random House, 2007).