After marching for over half a month, the 20,000-strong army finally approached Big South East Peace City, a crucial stronghold held by the Dongsheng military. This was a very important and ancient city which, to use an Earthling's concept, was the capital of the Qingqiu Clan.
It was only after this city had fallen that the Demon Clan's military began experiencing continuous defeat, with the subsequent wars almost completely one-sided. Therefore, for the Demon Clan, especially the Qingqiu Clan, capturing this city was critical to achieving complete victory in the first phase of their counterattack.
By the way, the Demon Clan had a poetic way of naming cities, simply calling them what they appeared, without overthinking the meaning of the names.
Take Big South East Peace, for instance; the word "Big" carries no special meaning, just like in "Great Tang" or "Great Ming". It was merely an act of self-praise, so the city should simply be called South Dongan City.