Why did France get involved in ww1?

France got involved in World War 1 because Austria-Hungary said that they would attack them if they did not fight. But when they joined the war many many people got killed and then they regretted even getting involved in this sort of mess. Other words they thought that they should just give up. But they didn't they went all the way through. It's amazing huh what I know is something special. When they went all the way through that war they thought that they were going to die, but they didn't they were alive. But now they are dead now.........I feel really bad for them because they were set up. When they were done with the war and they went home to their family, the other people of the war cam into their country and killed the people that lived. Now that is really sad but oh well.