The Odyssey has quite detailed passages describing how they served wine back in Ancient Greece - seems that the wine itself was sort of a concentrate that had to be watered down before serving. Polyphemus, a cyclops, gets quite drunk when he drinks undiluted wine, suggesting that the undiluted version was quite potent.
But yeast dies above a certain ABV, right? Unless you're using some distilled alcohol to fortify the wine like port, wouldn't wine (assuming it's made in the same general method) not be much stronger than 15-16% ABV?
Was Ancient Greek wine much stronger than this? If not, why did they dilute it (so that they could drink longer without getting too drunk?), and when did wine drinkers stop diluting wine?
Doesn't exactly answer your question (at least not the one in the title), but you may be interested in these answers from /u/Spoonfeedme and /u/Qweniden, on the differences between modern wine and ancient Greek/Roman. Also this other comment from Qweniden that they cite in that first post.