subiere

Tenuere tamen arcem Sabini. Atque inde postero die, cum exercitus Romanus inter Palatinum Capitolinumque collem instructus esset, non prius descenderunt in locum aequum quam Romani - ira et cupiditate arcis reciperandae accensi - montem subiere.

I’m getting a bit confused here…

The Sabines then held the citadel. And then the next day, whilst the Roman army was ordered between the the Palatine and Capitoline hill(s), they did not first descend from there [inde] to the same level as? / whilst? [quam] the Romans - (who were) inflamed with the desire that the citadel should be recovered - passed beneath the mountain [?]

…or they did not descend before (until) the Romans had passed underneath…?

I’m not sure what ‘subeo’ means in this context. Passed beneath? Ascended?

subiere – “went/came up to [the foot of]”

tamen – “however”

However, the Sabines held the citadel. And then, the next day, when the Roman army had been drawn up between the Palatine and Capitol Hills, they (the Sabines) did not come down onto level ground [locum aequum = “a level place”] before [non prius quam] the Romans, inflamed with anger and the desire to retake the citadel, came up to [the foot of] the mountain.

Thanks Qimmik.

Oh man, I think the dominant gerundive is one of the most awesome grammatical constructions! Goosebumps everytime I see one.