The other stratagem was of a different character, and was directed against a troop of cavalry. The Thessalian cavalry were renowned throughout the world. The broad plains extending through the heart of their country contained excellent fields for training and exercising such troops, and the mountains which surrounded it furnished grassy slopes and verdant valleys, that supplied excellent pasturage for the rearing of horses. The nation was very strong, therefore, in this species of force, and many of the states and kingdoms of Greece, when planning their means of internal defense, and potentates and conquerors, when going forth on great campaigns, often considered their armies incomplete unless there was included in them a corps of Thessalian cavalry. A troop of this cavalry had invaded Phocis, and the Phocaeans, conscious of their inability to resist them in open war, contrived to entrap them in the following manner. They dug a long trench in the ground, and then putting in baskets or casks sufficient nearly to fill the space, they spread over the top a thin layer of soil. They then concealed all indications that the ground had been disturbed, by spreading leaves over the surface. The trap being thus prepared, they contrived to entice the Thessalians to the spot by a series of retreats, and at length led them into the pitfall thus provided for them. The substructure of casks was strong enough to sustain the Phocaeans, who went over it as footmen, but was too fragile to bear the weight of the mounted troops. The horses broke through, and the squadron was thrown into such confusion by so unexpected a disaster, that, when the Phocaeans turned and fell upon them, they were easily overcome. These things had irritated and vexed the Thessalians very much. They were eager for revenge, and they were very ready to guide the armies of Xerxes into the country of their enemies in order to obtain it.