Thebans and...

[Jona Lendering]

This was rejected by the Athenians (perhaps not the wisest decision).

I beg to differ: Sparta did not offer any guarantees that it would not break the peace once it had obtained back its men. Cleon reasonably demanded a better offer, and I think the attack on Megara that comes immediately after the rejection of the peace offer can best be seen as a necessary action to achieve the conditions necessary for peace.

Had Megara been taken, Athens could have said something like "OK, we have cut off the road from the Peloponnese to Thebes, and we now have obtained some certainty that a peace treaty will not again be violated. Now let's talk business."

As it happened, Megara was not captured, and Brasidas reached Thrace, giving the war a completely different dimension.