+49.+ News being brought that Euthydemus[16] with his force was at Tapuria, and that a body of ten thousand horsemen were keeping guard at the passage of the river Arius, he decided to abandon the siege and attack these last. The river was three days’ march away. For two days therefore he marched at a moderate speed; but on the third, after dinner, he gave orders for the rest of his army to start next day at daybreak; while he himself, with the cavalry and light-armed troops and ten thousand peltasts, started in the night and pushed on at a great rate. For he was informed that the cavalry of the enemy kept guard by day on the bank of the river, but at night retired to a city more than twenty stades off. Having completed therefore the rest of the way under cover of night, the plains being excellent for riding, he got the greater part of his army across the river by daybreak, before the enemy came back. When their scouts told them what had happened, the horsemen of the Bactrians hastened to the rescue, and fell in with their opponents while on the march. Seeing that he must stand the first charge of the enemy, the king summoned the two thousand horsemen who were accustomed to fight round his own person; and issuing orders that the rest were to form their companies and squadrons, and take up their usual order on the ground on which they already were, he advanced with the two thousand cavalry, and met the charge of the advanced guard of the Bactrians. In this engagement Antiochus is reputed to have shown the greatest gallantry of any of his men. There was heavy loss on both sides: the king’s men conquered the first squadron, but when a second and a third charged, they began to be hard pressed and to suffer seriously. At that juncture, most of the cavalry being by this time on the ground, Panaetolus ordered a general advance; relieved the king and his squadrons; and, upon the Bactrians charging in loose order, forced them to turn and fly in confusion. They never drew rein before the charge of Panaetolus, until they rejoined Euthydemus, with a loss of more than half their number. The king’s cavalry on the contrary retired, after killing large numbers and taking a great many prisoners, and bivouacked by the side of the river. In this action the king had a horse killed under him, and lost some of his teeth by a blow on the mouth; and his whole bearing obtained him a reputation for bravery of the highest description. After this battle Euthydemus retreated in dismay with his army to the city of Zariaspa in Bactria.... BOOK XI