9. If the camp was at Tarascon, Scipio’s cavalry had a ride of sixty or seventy English miles, there and back, besides some fighting on the way; and after their return there was the embarcation of the baggage; so that Scipio could hardly have begun his march till the next morning or next afternoon. He may have been marching on three days, though not a full day’s march on the first day and perhaps not on the third; and he would entrench his camp each night with extra care, as the enemy were not far off. Even so, his progress seems a little slow; but had he gone ten miles further in the time, there would have been a serious check. 10. Ten miles above Tarascon the river Durance flows into the Rhone. Livy (xxi. 31) says that, of all the rivers of Gaul, the Durance was far the most difficult to cross, _longe difficillimus transitu_; and he mentions that it happened to be swollen by rains (_forte imbribus auctus_) at the time when Hannibal was there. If Hannibal had crossed the Rhone more than ten miles above Tarascon, he would have had the Durance between Scipio’s forces and his own; and Polybios says nothing to suggest that there was any obstacle between. 11. At this period the Romans had only a militia; and Scipio’s marches must not be calculated on the scale of marches by the regular army that Marius created a century later on. Still less should they be calculated from statements by Vegetius, who lived six centuries later and dealt with marches along Roman roads to established forts and towns. At this period a Roman force entrenched itself each night, and the entrenching took some time. 12. According to Polybios (iii. 49. 5–7) Hannibal marched up along the river after leaving his camp at the crossing of the Rhone, and arrived in four days at the Island, a populous and fertile place with the Rhone running along one side of it and the Scôras along the other. It was not strictly an island, but was (Polybios says) of the shape and size of the Delta of the Nile, with river on two sides and a range of mountains instead of the sea for the third side. Livy (xxi. 31) follows Polybios almost word for word in saying that Hannibal marched up along the Rhone to a district called the Island, where another river flowed into the Rhone. But he calls the other river the Arar, which is the Saône, and thus brings Hannibal up to Lyons, 200 miles from the sea. This would mean an average of 25 miles a day, the confluence being four days from the crossing and the crossing being four days from the sea, whereas Polybios gives an average of only 7 miles a day for the whole march and 10 miles a day for 250 miles out of the final 325 after the crossing of the Rhone: see paragraphs 3, 4.