Hoping to win back territory lost to Israel during the third Arab-Israeli war, Egyptian and Syrian forces launch a coordinated attack against Israel on Yom Kippur, the holiest day in the Jewish calendar. Taking the Israeli Defense Forces by surprise, Egyptian troops swept deep into the Sinai Peninsula, while Syria struggled to throw occupying Israeli troops out of the Golan Heights.
Israel's stunning victory in the Six-Day War of 1967 left the Jewish nation in control of territory four times its previous size. Egypt lost the 23,500-square-mile Sinai Peninsula and the Gaza Strip, Jordan the West Bank and East Jerusalem, and Syria the strategic Golan Heights. When Anwar el-Sadat became president of Egypt in 1970, he found himself leader of an economically troubled nation that could ill afford to continue its endless crusade against Israel. He wanted to make peace and thereby achieve stability and recovery of the Sinai, but after Israel's 1967 victory it was unlikely that Israel's peace terms would be favorable to Egypt. So Sadat conceived of a daring plan to attack Israel again, which, even if unsuccessful, might convince the Israelis that peace with Egypt was necessary.
In 1972, Sadat expelled 20,000 Soviet advisers from Egypt and opened new diplomatic channels with Washington, which, as Israel's key ally, would be an essential mediator in any future peace talks. He formed a new alliance with Syria, and a concerted attack on Israel was planned.
When the fourth Arab-Israeli war began on October 6, 1973, many of Israel's soldiers were away from their posts observing Yom Kippur, and the Arab armies made impressive advances with their up-to-date Soviet weaponry. Iraqi forces soon joined the war, and Syria received support from Jordan. After several days, Israel was fully mobilized, and the Israel Defense Forces began beating back the Arab gains at a heavy cost to soldiers and equipment. A U.S. airlift of arms aided Israel's cause, but President Richard Nixon delayed the emergency military aid for seven days as a tacit signal of U.S. sympathy for Egypt. In late October, an Egyptian-Israeli cease-fire was secured by the United Nations.
Although Egypt had again suffered military defeat at the hands of its Jewish neighbor, the initial Egyptian successes greatly enhanced Sadat's prestige in the Middle East and provided him with an opportunity to seek peace. In 1974, the first of two Egyptian-Israeli disengagement agreements providing for the return of portions of the Sinai to Egypt were signed, and in 1979 Sadat and Israeli Prime Minister Menachem Begin signed the first peace agreement between Israel and one of its Arab neighbors. In 1982, Israel fulfilled the 1979 peace treaty by returning the last segment of the Sinai Peninsula to Egypt.
For Syria, the Yom Kippur War was a disaster. The unexpected Egyptian-Israeli cease-fire exposed Syria to military defeat, and Israel seized even more territory in the Golan Heights. In 1979, Syria voted with other Arab states to expel Egypt from the Arab League. On October 6, 1981, Sadat was assassinated by Muslim extremists in Cairo while viewing a military parade commemorating the anniversary of the Yom Kippur War.