The 1978 South Lebanon conflict, also known as the First Israeli invasion of Lebanon and codenamed Operation Litani by Israel, began when Israel invaded southern Lebanon up to the Litani River in March 1978. It was in response to the Coastal Road massacre near Tel Aviv by Palestinian militants based in Lebanon.
Text from Wikipedia, licensed under CC BY-SA 4.0
The 49th anniversary falls on March 14, 2027.