From Bram Stoker's "Dracula":
At the very beginning of the seventeenth century it underwent a siege of three weeks and lost 13,000 people, the casualties of war proper being assisted by famine and disease.
From what I understand, the word "proper" modifies "war", in which case I presume I am right to believe that the closest definition of it is "strictly limited to a specified thing, place, or idea" (6th meaning presented in Merriam-Webster's dictionary), which somehow, at least to my impression, makes no difference? How would the meaning change if "proper" were to be removed from the sentence? Or does the word proper modify the part that comes after it?
This is the first time I have come across such a usage of the word, and perhaps I'm missing something, so I'd very much appreciate any help or input : )