When was the war of Lebanon?
This is a debatable answer.
Lebanon was part of the Ottoman Empire until 1918. In 1918, due to the Ottoman's loss in World War I, Lebanon became a French mandate. This means that the French had control of Lebanon, according to the League of Nations. It was granted it's independence in 1943; however, allied soldiers still occupied the country. The last French soldier did not leave until 1946.
Returning to the question, one could say that the "war of Lebanon" could be 1918.
However, there is a much more plausible war, the Lebanese Civil War. In 1975 civil war broke out in Lebanon. This bloody gruesome battle lasted until 1990. It left a very lasting and powerful scar on Lebanese society.
In truth, the correct answer to the question should be either 1918 or 1975, 1975 being the most logical.