The correct answer is Israel.

The Suez Crisis of 1956 was a major international conflict that began when Egypt nationalized the Suez Canal. The canal was previously controlled by British and French interests. This move angered both the UK and France, as the Suez Canal was a critical waterway for trade and oil transport.

In response, three countries—Israel, the United Kingdom, and France—made a secret plan known as the “Protocol of Sèvres.” According to this plan, Israel would invade Egypt first. Then, Britain and France would issue an ultimatum to both sides, pretending to act as peacekeepers. When Egypt refused, British and French forces would intervene under the excuse of separating the warring parties and take control of the canal.

On October 29, 1956, Israel launched the invasion by attacking Egypt’s Sinai Peninsula. Shortly after, Britain and France joined in the military operations. However, the international reaction was strongly against the invasion. The United States, the Soviet Union, and the United Nations all demanded a ceasefire.

Due to political pressure, especially from the U.S., the invading forces had to withdraw, and the United Nations sent a peacekeeping force.

In summary, although Britain and France also invaded later, Israel was the first country to invade Egypt during the Suez Crisis of 1956.