In crossing the Hindoo-Koosh from south to north Alexander probably marched by the pass of Bamian, which seems the only one among the four passes open to an army in the winter. See Wood’s Journey to the Oxus, p 195. The Baktrian leader Bessus, who had assumed the title of king, could muster no more than a small force, with which he laid waste the country, and then retired across the river Oxus into Sogdiana, destroying all the boats. Alexander overran Baktria with scarce any resistance; the chief places, Baktra (Balkh) and Aornos surrendering to him on the first demonstration of attack. Having named Artabazus satrap of Baktria, and placed Archelaus with a garrison in Aornos,[480] he marched northward towards the river Oxus, the boundary between Baktria and Sogdiana. It was a march of extreme hardship; reaching for two or three days across a sandy desert destitute of water, and under very hot weather, The Oxus, six furlongs in breadth, deep, and rapid, was the most formidable river that the Macedonians had yet seen.[481] Alexander transported his army across it on the tent-skins inflated and stuffed with straw. It seems surprising that Bessus did not avail himself of this favorable opportunity for resisting a passage in itself so difficult; he had however been abandoned by his Baktrian cavalry at the moment when he quitted their territory. Some of his companions, Spitamenes and others, terrified at the news that Alexander had crossed the Oxus, were anxious to make their own peace by betraying their leader.[482] They sent a proposition to this effect; upon which Ptolemy with a light division was sent forward by Alexander, and was enabled, by extreme celerity of movements, to surprise and seize Bessus in a village. Alexander ordered that he should be held in chains, naked and with a collar round his neck, at the side of the road along which the army were marching. On reaching the spot, Alexander stopped his chariot, and sternly demanded from Bessus, on what pretence he had first arrested, and afterwards slain, his king and benefactor Darius. Bessus replied, that he had not done this single-handed; others were concerned in it along with him, to procure for themselves lenient treatment from Alexander. The king said no more, but ordered Bessus to be scourged, and then sent back as prisoner to Baktra[483]—where we shall again hear of him. [480] Arrian, iii. 29, 3; Curtius, vii. 5, 1. [481] Arrian, iii. 29, 4; Strabo, xi. p. 509. Evidently Ptolemy and Aristobulus were much more awe-struck with the Oxus, than with either the Tigris or the Euphrates. Arrian (iv. 6, 13) takes his standard of comparison, in regard to rivers, from the river Peneius in Thessaly.