Israel invaded Egypt on October 29, 1956. Not too long after that, Britain and France also invaded the country, which began the Suez Crisis.
All three countries had a reason for wanting to invade the country. Israel and Egypt long had their own issues, especially when it came to their border.
France thought that Egypt's leader, Gamal Abdel Nasser, was helping the rebels in the French colony, Algeria. Nassar nationalized the Suez Canal in 1956.
This move prompted an alliance between Britain, France, and Israel. They thought they needed to retake what they believed to be theirs.
However, on October 29, 1956, Israel's troops invaded the country alone. The two European countries did not invade until two days later. By the time they got there, the fighting was in full swing.
Nassar had the full support of the Soviet Union, who came to his aid. They threatened the other countries with nuclear weapons.
President Dwight Eisenhower stepped in and diffused the situation. Rather matter of factly, he told the Soviets that they would regret getting involved.
He then turned his attention to France, Britain, and Israel. He informed them all that if they did not swiftly exit the country of Egypt that the U.S. would impose sanctions on them all.
The countries smartly chose to leave the country and return to their own, thus avoiding what could have been an all-out nuclear war.
For more about the Suez Canal Crisis, check out this video from the History channel.