The war launched against Israel today from Gaza will be remembered as the most shocking attack in the history of the Jewish state, with the Israel Defense Forces caught by surprise as Hamas managed, on one of the holiest days of the Jewish calendar, to seize at least 17 towns or kibbutzim, start murdering residents, and kidnapping others back to Gaza.

Israeli authorities are confident that the country will prevail, though citizens are staggered by how the Gaza-based terrorists took over several towns and kibbutzim near the Gaza border. It may be too soon to say what that portends, but it’s not too soon to suggest that there will be a political reckoning of a kind that followed the Yom Kippur war of 1973.

The stories are unfathomable. Israeli broadcasters are speaking with frightened southerners who whisper into their mobile phones from shelters, as Hamas terrorists maraude outside. According to officially published numbers, more than 100 Israelis have been murdered and many hundreds injured. These numbers are likely to climb significantly. Most worrisome is the yet unknown number of Israelis who were kidnapped by Hamas and taken into Gaza, which will complicate immediate and future military planning.

Speaking to public broadcaster Kan, one man, Yoni Asher, said he was out of his southern town when the attack was launched. After briefly speaking with his wife, the phone connection was lost. Using his wife’s phone GPS, he later discovered the device is now at Han-Yunis, in the heart of the Hamas-controlled Gaza Strip. His attempts to contact police, the army, and emergency services were unsuccessful. 

The complete chaos in the first hours of the attack underlined a feeling in the country that no one is in charge. Prime Minister Netanayhu’s government convened for an hours-long meeting at the Tel Aviv defense ministry headquarters. Mr. Netanyahu grimly addressed the country later, even as the army was struggling to retake the southern towns. 

Yet it’s possible that, at least for the moment, the catastrophe could have a unifying effect. In a sign that Israel’s internal divisions were suspended, a weekly country-wide anti-Netanyahu protest was called off. Leaders of anti-Netanyahu IDF veterans who have previously called on members to refrain from showing up for reserve duty, now are urging all to join the fight.   

Opposition leaders said they would back the government as war is launched. Yair Lapid, leader of the largest opposition party, Yesh Atid, met Mr. Netanyahu for an hour and expressed full support. Arab members of the Knesset are calling on their constituent Israeli citizens to back the country and refrain from attacks on police and the military. 

“Israel is united,” another opposition leader, Benny Gantz, said. “If someone among our enemies thinks this is an opportune moment, they would be disappointed.” He said that the war would take time and exact a heavy toll on Israelis, but added that those who envisioned the attack would be punished. He warned anyone planning to join the Hamas assault to beware of the IDF’s long hand.   

In recent years Hamas has increasingly joined the Iran-backed axis and has been armed, trained, and financed by the Islamic Revolutionary Guards Corps. Hamas leaders regularly visit Tehran and meet with leaders at the highest levels. Watching Israel’s internal fighting and its growing political division, Hamas and its Iranian backers likely concluded that the time was ripe for an all-out attack. 

Israeli security officials are warning other Iran-backed forces — in Syria, the West Bank, and, most worrisome, in Hezbollah-controlled Lebanon — against joining Hamas for a coordinated escalation of the war. Hezbollah harbors hundreds of rockets and accurate missiles that can hit targets across Israel. In recent months it has increased its border provocations, but as yet has refrained from the kind of all-out attack that Hamas launched Saturday. 

Dozens of world leaders have expressed sympathy with Israel. Some, like President Zelensky, stressed Israel’s right to defend itself. President Biden spoke with Mr. Netanyahu on the phone midday. The Pentagon made clear it would supply all of Israel’s military needs. Yet, some of the usual calls for “restraint” also seeped into official statements from several corners. 

The United Nations secretary-general, Antonio Guterres, “stressed that violence cannot provide a solution to the conflict,” urging the sides to instead conduct “negotiations leading to a two-state solution.”

Most worrisome, one Washington administration office  joined such calls. While “unequivocally” condemning the Hamas attack, Mr. Biden’s “Office of Palestinian Affairs” posted a now-deleted message on X, urging “all sides to refrain from violence and retaliatory attacks. Terror and violence solve nothing.” 

Such language, sure to intensify once Israel launches its counteroffensive in earnest, will fall on deaf ears in Israel, where for now all are outraged at the Hamas terror attack. One day after the 50th anniversary of the Yom Kippur war, Israelis are as bewildered as they were then by their military’s failure to detect preparation for a surprise launching of war. 

Comparisons to 1973 fill chat rooms and talk shows on television and radio. In some aspects, the failure of the defense officials to detect preparation for war is worse now than it was then. While the entire Yom Kippur war was fought by armies in the Sinai peninsula and the Golan heights, the Egyptian and Syrian forces failed at that time to take over any territory inside Israel’s pre-1967 borders.

On Saturday, Hamas occupied entire civilian towns and villages, while the IDF, at least initially, failed to protect them. Following a barrage of rockets, Hamas easily cut border barriers and used hang gliders and Zodiac type boats to infiltrate Israel’s territory. The high civilian casualty rates and future haggling over hostages that were taken to Gaza will be remembered long after Israel wins its war against Hamas.