Troiani ad muros urbis pugnant

[Isidia]

Hi!
I encounter this sentence in an exercise which I don't understand

Troiani ad muros urbis pugnant
The Trojans fought _______ the city walls

The correct answer is "ad", but I don't understand it. Ad means "to". So is the answer really correct?

I am very aware that prepositions in Latin and English are very different, so I might be too stuck with English.

I guess it is entirely fine to say "inter+accussativus"

I am in chapter 6 of Lingua Latina.

Thank you!

[mwh]

Yes the ad is a little odd with pugnant, but this could mean they fight "to” the city’s walls (~ usque ad “right up to”), or it could just mean “at” them, near them.