Israel’s most stunning military triumph—and that victory’s historic repercussions—has pushed aside all other issues in the nation’s politics to this day.

The war was as unexpected as a tsunami. It lasted just six days. And yet, 40 years later, it is still unfinished business. a More than any event except the establishment of the state, the Six-Day War shaped Israel’s history. It was the country’s greatest military victory and redrew the Middle East map—which makes it harder to remember that the war was unplanned, as were the conquests. They defied military theorist Carl von Clause witz’s classic principle that “war is policy by other means.” In this case, the policy needed to be invented afterward. Arguably, defining the purpose of Israel’s territorial gains in June 1967 is still Israel’s greatest political challenge.

“We… did not foresee the Six- Day War,” Shlomo Gazit, who headed the research department of military intelligence, admitted bluntly in a book written long afterward. As an example of what led to “short-sightedness” among intelligence officers, Gazit recounts that, in early 1967, he presented a report on the atrocious level of training among Egyptian tank crews. “If you’re right,” replied Armor Corps commander Yisrael Tal, “they have no possibility of contending with us militarily.” Tal was right about how Egyptians would perform in battle; military intelligence was wrong to think the battle wouldn’t happen.

Nor was conquest on the Israeli agenda. the military’s five-year plan, put together by Prime Minister Levi Eshkol and Chief of Staff Yitzhak Rabin, presumed that Israel could “realize fully its national goals” within Israel’s existing borders. The platform of Eshkol’s Mapai Party called for peace based on the “territorial integrity” of all Middle East countries—not for expansion.

Then a series of border clashes ignited a crisis. Egyptian President Gamel Abdel Nasser marched his troops into the Sinai Peninsula and blockaded the Straits of Tiran. Other Arab countries joined forces with Egypt, and within days Israel seemed to face destruction. “Because the victory was so brilliant, no one [on the outside] believed that the government thought the war would be disastrous,” an ex-official privy to all intelligence reports in 1967 told me many years afterward in his kibbutz living room.

Rabin’s initial battle plan was to take the Gaza Strip as a bargaining chip to force Egypt to reopen the straits. Moshe Dayan, appointed defense minister a few days before the war, decided that plan was too limited. He aimed at destroying the Egyptian Army and conquering most of the Sinai, but he intended to stop short of the Suez Canal. As for Jordan and Syria, the Israeli government hoped they would sit out the war.

On June 5, Israel launched its preemptive attack against Egypt. From then, confusion shared command. In the Sinai, field commanders ignored Dayan’s instructions and rolled all the way to the canal. Despite Israel’s warnings, Jordan’s King Hussein entered the war. When Israel counterattacked, the Israel Defense Forces got orders to take part of the West Bank. But Jordanian resistance crumbled, and the IDF marched to the Jordan River. Meanwhile, Dayan convinced the cabinet to postpone an offensive to stop Syrian artillery bombarding the Galilee. Then he changed his mind and sent the Army to take the Golan Heights anyway.

On June 10, when a United Nations cease-fire took effect, Israel had achieved its defensive goals—avoiding destruction, crippling the armies that threatened it and reopening the straits. But it had also overrun territory three times as large as Israel itself. Along with the joy of victory came a question: What was this land for?

That question provoked a debate that has pushed aside all other issues in Israeli politics to this day. So I found it striking, when I began to dig through historical documents from the first months after the war, that most of today’s positions on the future of the territories were formulated almost immediately. What has happened since is debate about their pros and cons. Clear-cut decisions have been rare.

Of course, most of the basic issues were known from the start. The war made Israelis feel vulnerable. So perhaps the purpose of the land was to provide safety. If it were kept permanently, Syria would not be able to fire artillery at the Galilee; Jordan could no longer threaten to cut Israel in two at its narrow waist. Egypt’s troops would be much farther from Israeli cities and would no longer hold Sharm al-Sheikh, the tip of Sinai that controlled the Straits of Tiran.

Then again, the ruling party’s prewar goal had been peace based on existing borders. So maybe the purpose of the territories was to pressure Arab neighbors to accept Israel’s existence and sign on to peace. Designed properly, the agreement would provide security. The land was a bargaining chip, a deposit.

Leaning toward the latter position, the cabinet decided 10 days after the war to secretly offer Egypt and Syria “a full peace treaty on the basis of the international border and Israel’s security needs.” If this didn’t mean a total pullout, it implied something close.

When Arab leaders met later that summer in Khartoum and ruled out formal peace, the Israeli position shifted. Moshe Dayan famously said he would prefer to have Sharm al-Sheikh without peace than peace without Sharm. Only after the 1973 Yom Kippur War did the pendulum swing back. That war cracked the belief that territory alone would protect Israel. Anwar al-Sadat’s offer of peace led to the Israeli decision to give back every last inch of the Sinai—the most definitive decision about occupied land in the last 40 years. That history shows how the absence or presence of an Arab partner making a credible diplomatic offer can influence Israeli politics.

Yet peace and security were never the only considerations. Another was the historical sense of ownership of the land of Israel, even if the extent of that homeland was unclear. For some Israelis—such as the mostly secular group of intellectuals and politicians who formed the Movement for the Whole Land of Israel in the summer of 1967—the war’s purpose was regaining Jewish patrimony, conveniently defined by the cease-fire lines. “No Israeli government has the right to give up the wholeness” of the land, the movement’s manifesto declared.

And for some religious Jews, the Whole Land was itself a means to hurrying messianic redemption. Rabbi Tzvi Yehuda Kook, spiritual leader of that camp, declared that giving up any part of the “inheritance of our fathers” was “a sin and a crime.” Kook’s followers eventually formed Gush Emunim, which spearheaded settlement in the West Bank.

But all arguments for staying put ran up against another concern: The occupied land was home to at least 1.1 million Arabs, almost all in Gaza and the West Bank, and with a high birthrate. Of the war, Eshkol was fond of saying afterward, “We got a lovely dowry. The trouble is that with dowry comes the wife”—referring to the land and the Arabs living there. As top officials pointed out immediately, keeping the West Bank and Gaza created an impossible choice: If Israel annexed them, it would eventually have an Arab majority—putting to rest Zionism’s goal of a Jewish state. Ruling the land while leaving the residents disenfranchised ran against Israel’s democratic character and would be regarded internationally as colonialism.

The first proposal to solve the problem by creating a Palestinian state was written before the war ended by Gazit’s department at military intelligence. Several weeks later, a secret panel discussing possibilities for the West Bank’s future criticized the plan because—strange as it sounds today— the state “would be regarded internationally as an Israeli puppet.”

The alternative was returning some or most of the West Bank to King Hussein. Cabinet minister and ex-general Yigal Allon proposed keeping East Jerusalem and the unpopulated desert along the Jordan River and giving the rest back. Hussein, in fact, was willing to make peace. The catch was that he insisted on a return to the prewar borders. There was no partner for the Allon Plan.

Eshkol himself, hoping to keep Gaza for Israel, set up a top-secret effort in 1968 to encourage Palestinian refugees to emigrate from the strip. The project flopped. Proponents of keeping all the land said that Jewish immigration would make up for the new Arab population. But dreams of mass aliya from the West remained a fantasy. A small increase in immigration from North America did not fulfill even a fraction of those proponents’ hope. In the 1990’s, Jews did flood into Israel from the former Soviet Union—but not enough to outweigh the Palestinian birthrate.

Soon after the war, labor party dissident Arie “Lova” Eliav and novelist Amos Oz argued that Israel must acknowledge that it was dealing not just with “Arab residents” but with a Palestinian people. Giving up the land taken in war could serve the purpose of ending the struggle between Jews and Palestinians over a shared homeland. That once-radical position became mainstream after the first Palestinian uprising 20 years ago. At last new possibilities seemed to open. The result was the Oslo Accord in 1993, which promised to resolve the dilemma of 1967.

Instead, Israel was bitterly divided. Protests escalated until a radical believer in the Whole Land assassinated Prime Minister Yitzhak Rabin in 1995. In 2000, the Oslo process collapsed, largely over an old dispute: Would Israel have to give up all of the West Bank, as the Palestinians demanded, or only most, as Israel proposed? The brutality of the new Palestinian uprising left Israelis wondering once more if there was a peace partner. Then again, could there be any point to trying to keep the “dowry” (the land) if divorce from the “wife” (the Palestinians) was so clearly needed?

So 40 years later, the question remains— overwhelming and unsolved. In part, we can blame the lack of another Sadat. In part, though, we must also acknowledge our own indecision. We have wanted to have our land and trade it away, to make peace and barricade ourselves. History shows that the arguments were mostly known the day after the fighting. But the war will really only be over when Israel, as a country, chooses the purpose of those six days in June.