de bello gallico, 4.26

It was fought by each fiercely. Our men, however, because they were able neither to preserve their ranks, nor to stand firmly, nor follow the standards, and someone from another ship was adding himself with which standards he had run up to, were greatly disturbed; the enemy indeed, with all the fords well-known, when from the shore they had caught sight of some individuals coming out from their ship, with the horses having been spurred on were attacking the impeded men, many were surrounding few, others were hurling weapons from the open side into the mass of men. Which when Caesar had learned (it), he ordered the skiffs of the war ships and likewise the scouting ships to be filled with soldiers, and whom he had seen laboring, to these he was sending aid. Our men, as soon as they stood on the dry land, with all of their own men having caught up, made an attack on the enemy and gave them into flight; and they were not able to follow farther because the cavalry was not able to hold course and to take the island. This one thing was lacking for Caesar to his previous good fortune.