Ok, the last four:
Medina (627) – The failure of the Meccans to capture the city (a clash more popularly known as ‘The Battle of the Trench’) meant that Muhammad’s power within Medina was secured, leading to his further conquests. Islam’s rapid rise in power would never have been accomplished had Medina fallen.
Castillons (1453) – The last battle of the Hundred Years War that all but completed the restoration of French control over the country (barring Calais). More than that, it was the first battle where cannon is recorded as being the crucial factor in the result.
Lepanto (1571) – Major European victory over the Ottoman Empire, halted the inexorable Muslim advances into the Balkans, and was the swan song of the oar powered naval age. It’s immense symbolic effect on Europe and the Middle East is enough to make it decisive.
Britain (1940) – Included for a number of factors. Firstly, it was the first major campaign to be fought almost entirely by air forces. Secondly, it halted the planned German invasion of Britain (which would have had an arguable result, but it would have happened). Thirdly, the immense morale effect it had cannot be understated(seriously, do not underestimate the effect “their finest hour” had on the war effort.) And lastly, along with Hastings, Azincourt, Gravelines, Waterloo and The Somme, the Battle of Britain is an ingrained part of that nations military culture and national ideology.
That’s Thirty. Marathon, Zama, Pharsalus, Adrianople, Medina, Hastings, Hattin, Ain Julut, Crecy, Orleans, Castillons, Lepanto, Gravelines, Breitenfeld, Vienna, Fontenoy, Cowpens, Valmy, Borodino, Waterloo, Hampton Roads, Wilderness/Spotsylvania, Sedan, Tsushima, the Marne, The Somme, Madrid, Britain, Pearl Harbour, Stalingrad.
21 are European. Four are Middle Eastern. Four in North America and one in Asia. Not geographically balanced I’ll admit, but that’s just the way it is.
Four naval clashes. One air battle. 20 exclusively land battles and four of ‘mixed’ genre.
I think it’s a good mixture. Anyone disagree?