Random people could still hit you, you need to protect yourself if you don't want them to.

And for the two DH thing, someone will always be able to have first strike unless you set a specific TIME that attacks are allowed between the two of you that you're both going to be online at, at which point you can go at each other simultaneously.

But imo a war shouldn't have "rules," you should just PM your country numbers to each other and each start hitting whenever you want, guy who hits twice first will be the one opening himself up to special attacks.