André Geraque Kiffer 
Persian Campaigns In The Medes Wars, 494 – 479 Bc [PDF ebook] 

A strategic operational effort between land forces and sea forces will be sought to keep the Greeks in doubt as to where the main action is. Land movement is best suited to meet the greatest enemy resistance, and once it has engaged it (not decisively as it was in the Thermopylae), neutralizing its ability to react will allow sea movement to fall to the rear of the Greek position and stand on the defensive tactics, not precipitating an attack as occurred on Plataea.