Up to this time, traders had always used mules or horses. Our oxen were an experiment, and it succeeded admirably; they even did better when water was very scarce, which is an important consideration. A few hours after the departure of the trading company, as we enjoyed a quiet rest on a hot afternoon, we saw beyond the river a number of horsemen riding furiously toward our camp. We all flocked out of the tents to hear the news, for they were soon recognized as traders. They stated that the caravan had been attacked, about six miles off in the sand hills, by an innumerable host of Indians; that some of their companions had been killed; and they had run, of course, for help. There was not a moment's hesitation; the word was given, and the tents vanished as if by magic. The oxen which were grazing near by were speedily yoked to the wagons, and into the river we marched. Then I deemed myself the most unlucky of men; a day or two before, while eating my breakfast, with my coffee in a tin cup--notorious among chemists and campaigners for keeping it hot--it was upset into my shoe, and on pulling off the stocking, it so happened that the skin came with it. Being thus hors de combat, I sought to enter the combat on a horse, which was allowed; but I was put in command of the rear guard to bring up the baggage train. It grew late, and the wagons crossed slowly; for the river unluckily took that particular time to rise fast, and, before all were over, we had to swim it, and by moonlight. We reached the encampment at one o'clock at night. All was quiet, and remained so until dawn, when, at the sound of our bugles, the pickets reported they saw a number of Indians moving off. On looking around us, we perceived ourselves and the caravan in the most unfavorable defenceless situation possible--in the area of a natural amphitheatre of sand hills, about fifty feet high, and within gun-shot all around. There was the narrowest practicable entrance and outlet.