Over the spring and summer of 1973, there had been several warning signs that the Egyptians and the Syrians were considering launching an attack. Many additional signs were received in late September and early October. King Hussein of Jordan had even made a secret visit to Israel to warn Israel that an attack was coming. All of the warning signs were discarded by the head of Military Intelligence and others; they were all convinced that the Arabs would not attack until they had parity.
Meanwhile, the airforce had learned the lessons of the War of Attrition and knew that Egyptian and Syrian Sam sites were significant dangers to the dominance of the IAF. As a result, the IAF had developed an elaborate plan to eliminate the threat. It, however, had to be carried out before the airforce could engage in any other missions.
On Yom Kippur Eve, October 5, 1973, more and more signs pointed to an imminent attack, but still, the intelligence kept claiming the chances of war were low. However, the regular armed forces were put on the highest alert below war, and the airforce was quietly instructed to activate their reserves. Overnight intelligence came in that indicated that without a doubt, war was imminent. The data had pointed to a conflict beginning at 5 PM. The government decided on Yom Kippur morning the begin an immediate call up of the reserves. The IDF requested permission to launch a preemptive raid on the Egyptian and Syrian air forces, but Golda ruled it out fearing American support might be withheld later if Israel was the one attacking

 

At 2 PM, an artillery barrage began against Israeli position along the Suez Canal known as the Bar-Lev Line. As soon as the artillery attacks ended, commandos landed both along the Canal and at points inside Sinai. Along the Canal, they were followed by troops ferried across the Canal in small boats. The Egyptians were able to capture most of the Israeli installations on the Canal's east bank. Attempts to counterattack were repulsed by the Egyptians using anti-tank and anti-aircraft missiles.

It was, however, the Syrian front that was most dangerous. There were miles and miles of desert between the Canal and Israel proper, but if the Syrians could break through the Golan Heights, they could be in the Galilee in one day. The Syrian war plans had assumed they would accomplish that in one day. The odds were in their favor. On the morning of October 6, 1,400 Syrian tanks were facing 177 Israeli tanks. 11 Israeli artillery batteries vs. 115 Syrian and 200 Israeli infantrymen vs. 40,000 Syrians. The small Israeli forces on the Golan fought a desperate battle for 24 hours, holding back the Syrians. Losses were heavy, and most of the Southern Golan was lost. However, by Sunday night, the first reserve tank division was starting to arrive. They arrived with no time to spare and managed to hold the line, end the Syrian assault and go and eventually go on the offensive where soldiers advanced to Sasa and captured the summit of Mt. Hermon.

On the Egyptian front, the first Israeli counterattack on the third day of the war failed, and Israelis took up defensive positions. The Egyptians, however, attempted a significant attack on October 14, which was defeated by the IDF. Israel then turned to the offensive after a difficult battle at the Chinese Farm. Ariel Sharon led the first Israeli forces across the Canal They soon surrounded the third Egyptian army. As the immensity of the Israeli threat became clear, an immediate cease-fire was called for. After a brief confrontation between the United States and the Soviet Union, a fire went into effect on October 22. The cost of the war to Israel was severe; over 2,000 Israelis were killed and 10,000 wounded.