Rome vs. Parthia, essay help?

[Jona Lendering]

Hmmm, it seems then that I'll have to either change my topic or write about why the Romans and Persians fought so many wars at all.

You may consider another question: "What were the war aims, and to what extent were they achieved?"

why the Romans eventually gave up on holding most of Germany.

Good question, but complex. Even modern historians repeat hoaxes like "the Romans tried to take the Elbe as border" (no evidence), "the Romans could give up Germany because it was poor" (that's what Tacitus says, but it is untrue). I have noticed another problem here.