On May 14, 1948, the British Mandate officially expired. That same day, the Jewish National Council issued the Declaration of the Establishment of the State of Israel. About 10 minutes later, President Truman officially recognized the State of Israel, and the Soviet Union also quickly recognized Israel. However, the Palestinians and the Arab League did not recognize the new state, and the very next day, armies from Egypt, Syria, Lebanon, and Iraq invaded the former British Mandate to squelch Israel, while Saudi Arabia assisted the Arab armies. Jordan would also get involved in the war, fighting the Israelis around Jerusalem. 

Initially, the Arab armies numbered over 20,000 soldiers, but the Zionist militia groups like the Lehi, Irgun, and Haganah made it possible for Israel to quickly assemble the Israel Defense Forces, still known today simply as the IDF. By the end of 1948, the Israelis had over 60,000 soldiers and the Arab armies numbered over 50,000.

In early 1949, Israel began signing armistices with Egypt, Jordan, and Syria, which left Israel in control of nearly 75% of the lands that were to be partitioned into the two states under the 1947 plan. Jordan now occupied Judea and Samaria, which later became known as the West Bank due to its position on the western bank of the Jordan River. Jordan also occupied three quarters of Jerusalem, with the Israelis controlling only about a quarter in the western part of the city. To the west, Egypt occupied the Gaza Strip. The new armistice lines became known as the “Green Line”, and the conflict has continued to involve those lines and the issues that were contested in a war now nearly 70 years old.

In early June 1967, the Israelis captured Jordanian intelligence that indicated an invasion was imminent. On June 5, the Israelis launched a preemptive attack that knocked out the air forces of its Arab neighbors. Over the next six days, the Israelis overwhelmed the Egyptians in the west, destroying thousands of tanks and capturing the Gaza Strip and the entire Sinai Peninsula. At the same time, Israel drove the Jordanians out of Jerusalem and the West Bank, and it captured the Golan Heights from Syria near the border of Lebanon.

With realities changing on the ground, Palestinian resistance changed tactics and locations, and the tension caused by Palestinian attacks originating from Jordan would eventually lead to the expulsion of the PLO from Jordan. In conjunction with that, the notorious Palestinian group, Black September, would launch one of the most famous terrorist attacks of the 20th century at the Olympics in Munich in 1972, and that would touch off some of the Israeli Mossad’s most legendary operations as the Israelis sought to track down those responsible for the attack.

Black September: The History and Legacy of the Conflict Between the Palestinians and Jordan in 1970 looks at the fighting and its effects on the Middle East.