Advance toward the Loire

In 732, the Umayyad advance force was proceeding north toward the River Loire having outpaced their supply train and a large part of their army. Essentially, having easily destroyed all resistance in that part of Gaul, the invading army had split off into several raiding parties, while the main body advanced more slowly.

The Umayyad attack was likely so late in the year because many men and horses needed to live off the land as they advanced; thus they had to wait until the area's wheat harvest was ready and then until a reasonable amount of the harvest was threshed (slowly by hand with flails) and stored. The further north, the later the harvest is, and while the men could kill farm livestock for food, horses cannot eat meat and needed grain as food. Letting them graze each day would take too long, and interrogating natives to find where food stores were kept would not work where the two sides had no common language.

A military explanation for why Eudes was defeated so easily at Bordeaux and at the Battle of the River Garonne after having won 11 years earlier at the Battle of Toulouse is simple. At Toulouse, Eudes managed a basic surprise attack against an overconfident and unprepared foe, all of whose defensive works were aimed inward, while he attacked from the outside. The Umayyad forces were mostly infantry, and what cavalry they had never got a chance to mobilise and meet him in open battle. As Herman de Carinthia wrote in one of his translations of a history of al-Andalus, Eudes managed a highly successful encircling envelopment which took the attackers totally by surprise — and the result was a chaotic slaughter of the Muslim forces.

At Bordeaux, and again at the Battle of the River Garonne, the Umayyad forces were cavalry, not infantry, and were not taken by surprise, and given a chance to mass for battle, this led to the devastation of Eudes's army, almost all of whom were killed with minimal losses to the Muslims. Eudes's forces, like other European troops of that era, lacked stirrups, and therefore had no heavy cavalry. Virtually all of their troops were infantry. The Umayyad heavy cavalry broke the Christian infantry in their first charge, and then slaughtered them at will as they broke and ran.

The invading force went on to devastate southern Gaul. A possible motive, according to the second continuator of Fredegar, was the riches of the Abbey of Saint Martin of Tours, the most prestigious and holiest shrine in Western Europe at the time. Upon hearing this, Austrasia's Mayor of the Palace, Charles Martel, collected his army and marched south, avoiding the old Roman roads and hoping to take the Muslims by surprise. Because he intended to use a phalanx, it was essential for him to choose the battlefield. His plan — to find a high wooded plain, form his men and force the Muslims to come to him — depended on the element of surprise.

Battle