How were the Greeks used geography to their advantage in fighting the Persians at Thermopylae and Salamis.?

Holding the pass at Thermopylae was a ploy to force a sea battle in the adjacent strait of Artemesion in an attempt to destroy the Persian sea threat to the Greek city-states.

It failed, and the ir next try was at Salamis succeeded. With their sea advantage gone, the Persians could not supply their army by sea and had to send half of it home. And the Greek city-states were able to stop keeping their armies at home to defend the cities, and sent them out to unite and defeat the Persian army at Plataea.