While this certainly looks like a noble clause I think if you look through history you will find many instances of wars starting by this very same reasoning. One nation (or one ruler if you really go back) assumes that 'something' rightfully belongs to them and then proceed to attempt to claim it back. I'm sure you could name at least a couple conflicts going on right now which could fall under that category. In some cases you could say that was just an excuse for expanding territory, in others you could said they honestly did believe that they though something of theirs was taken. It's only something a 3rd party observer could judge.