[1967 R50/2]

You've give short shift to Naval engagements. Only the Armada is mentioned.

1 Of ancient battles, probably the most decisive was Actium. It assured the fate of the Roman Republic/Empire for centuries.

In the Eastern world, without a doubt Red Cliff was the most decisive battle.

2. During the middle ages,...well, let's face it, the western world was so fragmented that there were no lasting, decisive victories to be had either on land or sea. In the east, you could say the failed invasion of Japan by Kublai Khan was certainly decisive, even though it was not truly" a battle." It ensured Japanese nationhood uninterrupted into the modern era.

3. In the renaissance world, as already mentioned, the defeat of the Spanish Armada was key. Lepanto, as mentioned was also crucial, but I do not give it the weight of the Armada. It would have given the Turks better control of the trade routes, but hardly would indicate the conquest of Europe.

4. In the Napoleonic era...clearly Trafalgar cannot go without notice.

5. In the modern era: Midway. Battle could have gone either way and would really have decided the fate of the war in the Pacific.

I will grant you that WW2 wasn't decided in any one battle, but surely several battles were more key than others. On land, two were truly decisive: Stalingrad, and Kursk. Stalingrad halted the Wehrmacht advance forever and Kursk gutted them. After Kursk, it was just a matter of time before Hitler lost. Even if Normandy never took place.