The war began with a massive and successful Egyptian crossing of the Suez Canal. After crossing the cease-fire lines, Egyptian forces advanced virtually unopposed into the Sinai Peninsula. After three days, Israel had mobilized most of its forces and managed to halt the Egyptian offensive, settling into a 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. Within three days, however, Israeli forces had managed to push the Syrians back to the pre-war ceasefire lines. They then launched a four-day counter-offensive deep into Syria. Within a week, Israeli artillery began to shell the outskirts of Damascus. As Egyptian president Anwar Sadat began to worry about the integrity of his major ally, he believed that capturing two strategic passes located deeper in the Sinai would make his position stronger during the negotiations. He therefore ordered the Egyptians to go back on the offensive, but the attack was quickly repulsed. The Israelis then counterattacked at the seam between the two Egyptian armies, crossed the Suez Canal into Egypt, and began slowly advancing southward and westward towards Suez [51][52] in over a week of heavy fighting that inflicted heavy casualties on both sides.
