Explanation:

- (1)______: "Caused" or "inflicted" would fit the context of the sentence, as it talks about the unprecedented damage of the war.

- (2)______: The comparison here suggests using "Unlike" as the word following it, contrasting earlier wars with the one in question.

- (3)______: The phrase suggests that civilians were previously not involved. "Largely" could precede "not involved" to show extent.

- (4)______: "Confined" is used here to indicate limits or restrictions. In this context, casualties were primarily limited to militaries.

- *Option 1: "Belonged" wouldn't fit here as it implies ownership or association, not limitation.*

- *Option 2: "Confined" fits well, implying casualties were mainly restricted to armies.*

- *Option 3: "Restrained" doesn’t convey the idea of casualty limitation.*

- *Option 4: "Bound" suggests being tied or obligated, not applicable to limiting casualties.*

- (5)______ : "That" or "which" could fit here as a relative pronoun introducing the clause describing the war.