Ocean Floor...

Don't you lack resources to buy an army without a capital?

I have enough :D
There are crypts, dwarven mines, and medusa lairs – we gather gold from there. And it just lies around, you just need to collect it. As a rule, I build levels 1-6 in a city or castle. "Why warriors?" because your hero will be leveled up due to battles, you will have troops, and you will have money. In your case (capital), there will only be hope for money and a big waste of time.
4 months is insanely long, even for HotA. A month is more than enough, and for computers, it's even less.