The Frankish leader chose the battlefield. Moving his army over the mountains and avoiding the open roads, he escaped detection until positioning his men on a high, wooded plain. Martel had carefully chosen the battlefield, in large part knowing the hills and trees surrounding his position would greatly hinder the Muslim cavalry. For seven days, the two armies skirmished and maneuvered, with the Islamic forces recalling all their raiding parties, so that on the seventh day, their army was at full strength. Martel also received some reinforcements, though most historians agree he was badly outnumbered during the battle. Martel trained his men to fight in a large square, similar to the ancient Greek phalanx formation, to withstand the Muslim heavy cavalry. The Franks held their defensive formation all day, and repulsed repeated charges by the Muslim heavy cavalry.