The Six-Day War (Arabic: حرب الأيام الستة‎, Ḥarb al‑Ayyam as‑Sitta or more commonly Arabic: حرب 1967‎, Ḥarb 1967; Hebrew: מלחמת ששת הימים‎, Milhemet Sheshet Ha‑Yamim), also known as the 1967 Arab-Israeli War, the Third Arab-Israeli War, Six Days' War, an‑Naksah (The Setback), or the June War, was fought between Israel and Arab neighbors Egypt, Jordan, and Syria. The nations of Iraq, Saudi Arabia, Sudan, Tunisia, Morocco and Algeria also contributed troops and arms to the Arab forces.

In May 1967, Egypt's president Nasser expelled the United Nations Emergency Force (UNEF) from the Sinai Peninsula. The peacekeeping force had been stationed there since 1957, following a British-French-Israeli invasion which was launched during the Suez Crisis. Egypt amassed 1,000 tanks and nearly 100,000 soldiers on the border and closed the Straits of Tiran to all ships flying Israeli flags or carrying strategic materials, receiving strong support from other Arab countries. On June 5, 1967, Israel launched a pre-emptive attack against Egypt's airforce. Jordan, which had signed a mutual defence treaty with Egypt on May 30, then attacked western Jerusalem and Netanya. At the war's end, Israel had gained control of the Sinai Peninsula, the Gaza Strip, the West Bank, East Jerusalem, and the Golan Heights. The results of the war affect the geopolitics of the region to this day.

Source: Wikipedia