Original: The Athenian general Themistocles had proposed that the allied Greeks block the advance of the Persian army at the pass of Thermopylae, and simultaneously block the Persian navy at the Straits of Artemisium.
Simplified: The Athenian general Themistocles suggested the Greek allies should block the Persian army at the pass of Thermopylae, and block the Persian navy at the Straits of Artemisium.