The Yom Kippur War, also known as the Ramadan War, the October War, the 1973 Arab–Israeli War or the Fourth Arab–Israeli War, was an armed conflict fought from 6 to 25 October 1973 between Israel and a coalition of Arab states led by Egypt and Syria. The majority of combat between the two sides took place in the Sinai Peninsula and the Golan Heights—both of which were occupied by Israel in 1967 — with some fighting in African Egypt and northern Israel. Egypt's initial objective in the war was to seize a foothold on the eastern bank of the Suez Canal and subsequently leverage these gains to negotiate the return of the rest of the Israeli-occupied Sinai Peninsula.The war began on 6 October 1973, when the Arab coalition jointly launched a surprise attack against Israel on the Jewish holy day of Yom Kippur, which had occurred simultaneously with the Islamic holy month of Ramadan in that year. Egyptian and Syrian forces crossed their corresponding ceasefire lines with Israel and invaded the Sinai Peninsula and the Golan Heights, respectively. Following the outbreak of hostilities, both the United States and the Soviet Union initiated massive resupply efforts to their respective allies during the war, which led to a near-confrontation between the two nuclear-armed superpowers.The fighting commenced with a massive and successful crossing of the Suez Canal by the Arab coalition; Egyptian forces crossed the ceasefire lines with Israel and advanced virtually unopposed into the Sinai Peninsula. However, Israel mobilized most of its forces three days later and halted the Egyptian offensive, resulting in a military stalemate. The Syrians coordinated their attack on the Golan Heights to coincide with the Egyptian offensive and initially made threatening gains into Israeli-held territory. After three days of heavy fighting, Israeli forces had pushed the Syrians back to the pre-war ceasefire lines. The Israeli military then launched a four-day-long counter-offensive deep into Syria. Within a week, Israeli artillery began to shell the outskirts of the Syrian capital of Damascus, and Egyptian president Anwar Sadat began to worry about the deteriorating integrity of the Arab coalition's leadership. Sadat believed that capturing two strategic mountain passes deeper within the Sinai Peninsula would make the Arab position stronger during post-war negotiations with Israel, and subsequently ordered Egyptian forces to mount another offensive against the Israelis, which was quickly repulsed. Israeli forces subsequently counter-attacked at the seam between the two Egyptian formations, crossed the Suez Canal into Egypt, and slowly began advancing southward and westward towards Suez City in over a week of heavy fighting that resulted in large casualties on both sides.On 22 October, an initial ceasefire brokered by the United Nations unravelled, with each side blaming the other for the breach. By 24 October, the Israelis had improved their positions considerably and completed their encirclement of the Egyptian Third Army and Suez City, bringing them within 100 kilometres (62 mi) of the Egyptian capital of Cairo. This development led to dangerously heightened tensions between the United States and the Soviet Union (allied with Israel and with the Arab states, respectively) and a second ceasefire was imposed cooperatively on 25 October to officially end the war.

The Yom Kippur War had far-reaching implications; the Arab world had experienced humiliation in the lopsided rout of the Egyptian–Syrian–Jordanian alliance in 1967, but felt psychologically vindicated by early successes in the 1973 conflict. The Israelis recognized that, despite impressive operational and tactical achievements on the battlefield, there was no guarantee that they would always dominate the Arab states militarily, as they had done consistently throughout the First Arab–Israeli War, the Second Arab–Israeli War and the Third Arab–Israeli War; these changes paved the way for the Israeli–Palestinian peace process. The 1978 Camp David Accords that followed the war saw Israel return the entire Sinai Peninsula to Egypt and the subsequent 1979 Egyptian–Israeli peace treaty, which marked the first instance of an Arab country recognizing Israel as a legitimate state. Following the achievement of peace with Israel, Egypt continued its drift away from the Soviet Union and eventually left the Soviet sphere of influence entirely.