Very very often not possible on deity. You can HA at most 2 civs and then longbows appear which are a brick wall for any ancient/classical unit. Medieval warfare is a slog with castles and whatnot and very often completely ruins your economy. And workerstealing - the AI usually protects its workers with archers so unless you have t30 chariots or quechas good luck. Even if not, declaring war early causes them to spam archers, making killing them that much more a PITA. EDIT: I see what you mean by “won” as in winning position. I’m still not sold - early war is very costly and can set you back in development by over 500 years. They also have a chance of failing especially if enemy is agg and/or has metal. Forget about lib or keeping in the tech race at least until the renaissance. Finally the point about workerstealing stands - they guard their workers almost always IIRC. There *are* cases where early wars are immensely helpful or even needed; however they are far from the revolutionary find you describe them as.