WI: Sparta loses the Battle of Mantinea?

Roughly halfway through the Peloponnesian War, Athens and Sparta concluded a "peace treaty" due to the capture of a number of Spartiates by Athens in an earlier action and campaigns by Sparta against Athenian-dominated cities in Macedonia and Thrace. However, both sides continued to maneuver for domination, influenced by the possible power of the city Argos, which was located in the Peloponnesian peninsula but had traditionally been hostile to Sparta. Athens signed an alliance with Argos and some of their allies, and together they moved to conduct operations in the Peloponnesian peninsula against enemies of Argos and her allies. The Spartans sent forces led by King Agis against the allies twice, but the first time he was persuaded to leave without fighting despite having a superior situation, which led to harsh criticism in Sparta. Nevertheless, he was sent out again, whereupon he engaged and defeated the allies and broke up the Argos-Athens alliance, ending any chance of Athens neutralizing Sparta on land.

It struck me on reading the description of the battle given by Thucydides that the situation faced by both sides was very similar in some respects to the later Battle of Leuctra, where Thebes famously smashed the dominance of Sparta. In particular, in both battles the elite wing of the non-Spartan army was able to smash the forces in front of it, opening a chance to force the disintegration of the Spartan line (here, the right wing of the allied army, which was composed of the Mantinean and elite Argive forces, destroyed the Spartan left, composed of the Scritae, a non-Spartan people traditionally assigned to that side). However, whereas at Leuctra this caused the disintegration of the Spartan formation, at Mantinea the allies, instead, were beaten; while their elite was defeating the Scritae, their less elite forces to their left were fleeing from the Spartans on the shock of facing the relatively elite Spartan center, under the direct command of King Agis, with some of them fleeing even before entering battle (according to Thucydides). Thus, the victory of the allied right ended up benefiting them not at all, because they were flanked from the left and ended up fleeing along with most of the rest of their army. In the end, although the Spartans took moderate losses, the allies took much heavier casualties.

Hence, it is tempting to ask what would have happened if Mantinea had ended up being like the later Leuctra, whether because the allied contingents stand and fight rather than fleeing, or because of novelties in strategy from the allied command like those adopted at Leuctra. The army amassed by Sparta at Mantinea was very large by the standards of the time, and if it had taken substantial losses it could have permanently weakened Sparta and broken their hegemony over the peninsula. Additionally, the capture of Mantinea would have greatly weakened Sparta by blocking their main route out of the peninsula, thus isolating them from all of their allies. Together, these seem like they would have led to a decisive Athenian victory in the overall war, though I suspect that, like Sparta herself or Thebes later, the Athenians would eventually have destroyed themselves (perhaps even in the decisive Sicilian Expedition, in this timeline regarded as a separate though related conflict).

Thoughts?
 
I think it would have been a decisive victory over Sparta (maybe with the helots/Messenians being freed), but it wouldn't have led to peace in the region any more than Napoleon's repeated victories led to peace. Thebes would probably replace Sparta as the leader of the anti-Athenian coalition and the war would have gone on until the Persians decide to get rid of the Athenians in Ionia once and for all.
 
I think it would have been a decisive victory over Sparta (maybe with the helots/Messenians being freed), but it wouldn't have led to peace in the region any more than Napoleon's repeated victories led to peace. Thebes would probably replace Sparta as the leader of the anti-Athenian coalition and the war would have gone on until the Persians decide to get rid of the Athenians in Ionia once and for all.

Oh, I don't suppose it would. Neither Sparta nor Thebean hegemony led to peace, after all. But it would certainly change the character and nature of what came afterwards.
 
Oh, I don't suppose it would. Neither Sparta nor Thebean hegemony led to peace, after all. But it would certainly change the character and nature of what came afterwards.

Yeah it would, considering Spartan defeat frees Athens from having to focus on two fronts (well, not to such an extent anyway - Corinth will still likely be hostile no matter what given Athenian meddling in Corfu), and I'm not sure how the Athenian assembly/Alcibiades will find a justification for invading Doric Syracuse now that the main Doric power has been eliminated, so it's quite likely that they will put all of their energies into crushing Thebes after that.

Given the disparity between Theban and Athenian army leadership showcased at Delium, I'm slightly sceptical that Athens will be able to defeat Thebes on land. But then again, they defeated Sparta ITL...

Given the impending disaster for Thebes, I find it hard to believe that the Thebans won't ask for whatever Persian support is available to resist Athens. And of course it has to be in the Persian interest to do so, if only to reduce the Greek Ionian holdings. In terms of economic muscle, Persia can definitely beat Athens - as demonstrated OTL with Sparta's mercenary fleets.
 
Temporarily at least, you may very well see Thebes bow out in some kind of truce-but it won't last long. Longterm, Sparta can't recover to their former strength unless they undergo some radical reforms. Athens is actually in the drivers seat-if they can pull off a victory over Thebes, it will be very interesting to see what happens from there, Persian gold or no Persian gold.

Developments in Thessaly, particularly in Pherai, should be impacted as well.
 
Yeah it would, considering Spartan defeat frees Athens from having to focus on two fronts (well, not to such an extent anyway - Corinth will still likely be hostile no matter what given Athenian meddling in Corfu), and I'm not sure how the Athenian assembly/Alcibiades will find a justification for invading Doric Syracuse now that the main Doric power has been eliminated, so it's quite likely that they will put all of their energies into crushing Thebes after that.
Remember, if they win at Mantinea they have Argos and a good chunk of the Peloponnese as allies, at least for the moment. Corinth will be too busy seeing to her own southwards frontiers to be much of a factor in Attica.

Given the disparity between Theban and Athenian army leadership showcased at Delium, I'm slightly sceptical that Athens will be able to defeat Thebes on land. But then again, they defeated Sparta ITL...
Well, Delium took place before Mantinea, so perhaps that could be a good point of departure. One or more of the Athenian generals involved in the latter venture takes note of the tactics used by the Boeotians in the former battle and persuades his comrades to apply them against the Spartans. Even without any great cleverness it was a fairly near-run thing (Agis made certain mistakes during battle), so this could plausibly lead to an allied victory with moderate Spartan casualties. In turn, this general's prestige could lead to other Athenian generals adopting the same tactics, which perhaps could allow Athens to hold her own on land against the Thebans and their allies.

Given the impending disaster for Thebes, I find it hard to believe that the Thebans won't ask for whatever Persian support is available to resist Athens. And of course it has to be in the Persian interest to do so, if only to reduce the Greek Ionian holdings. In terms of economic muscle, Persia can definitely beat Athens - as demonstrated OTL with Sparta's mercenary fleets.
True, though the Persians might have more trouble getting an alliance together. The key thing that they will need to do is to break up the alliance with Argos, in particular; I imagine something like the Corinthian War, perhaps after a brief period of peace, where an unnatural alliance of the more powerful not-actually-subjugated states (I'm thinking an alliance of Argos, Sparta, Thebes, and Corinth) confronts Athens under Persian influence. This will take a while to be victorious, though, if the OTL Peloponnesian War is any indication. Even with Persian gold, it took a lot of Athenian stupidity for their fleets to be overwhelmed.
 
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