The form should be nominative -- meritus
-- because it agrees with Caesar, even though it's indirect speech. I can't find a specific citation for this point in Allen & Greenough, but examples 3, 4, 5 and 6 in in section 582 illustrate this.http://www.perseus.tufts.edu/hopper/text?doc=Perseus%3Atext%3A1999.04.0001%3Asmythp%3D582
would probably be omitted in "real" Latin. And in any event, the active verb mereo
(in this case, meruisse
), which exists alongside the deponent mereor
, would result in a smoother sentence. http://www.perseus.tufts.edu/hopper/morph?l=mereor&la=la&can=mereor0#lexicon
I would use the imperfect putabatur
here, since this was a general state of affairs that didn't suddenly occur at a particular moment in time. But I'm not sure that puto
is the right verb here. Maybe censeo
would be better.
You might be better off finding a mnemonic sentence that doesn't involve a passive verb of indirect discourse.