 Complete the following phrase:  In 480 BC, Darius successor Xerxes I sent a much more powerful force of 300,000 by land, with 1,207 ships in support, across a double pontoon bridge over the Hellespont. This army took Thrace, before descending on Thessaly and Boeotia, whilst the Persian navy skirted the coast and resupplied the ground troops. The Greek fleet, meanwhile, dashed to block Cape Artemision. After being delayed by Leonidas I, the Spartan king of the Agiad Dynasty, at the Battle of Thermopylae a battle made famous by the 300 Spartans who faced the entire Persian army, Xerxes advanced into Attica, and captured and burned Athens. The subsequent 