The river Colorado was crossed on rafts. Disease and desertion thinned the ranks. The wounded died for lack of proper treatment, as there was not a case of surgical instruments in the army. They extracted arrow-heads from their wounds with probes improvised from ramrods. Every morning's roll-call showed a dwindling force. Beef was the only food left. Two men quarrelled over a handful of parched corn, and one shot the other dead. They were in rags. The President of Sonora, wearing a boot on one foot, a shoe on the other, fared no better than his followers. Those followers soon numbered less than fifty. A council of war was held, and it was decided to return to San Vincente. The Mexicans hung upon their flanks and rear, cutting off every straggler. Recrossing the mountains, they narrowly escaped annihilation in a gorge which widened out at the middle to a plateau of half a mile across, with a narrow opening at either end. Half way across the plains the Indians appeared on flank and front and opened a galling fire. Walker here showed coolness and generalship. Leaving twelve men hidden in a clump of bushes under command of Lieutenant P. S. Veeder, a cool young soldier, afterwards distinguished in Nicaragua, he retreated with the rest of the command towards the entrance of the valley. The passage had already been closed by the enemy's forces, who met the retiring party with an ill-aimed volley of arrows and bullets. At the same time those guarding the other pass joined their friends on the flanks in charging the Americans. As they passed the thicket where Veeder and his men lay in ambush, they received a deadly volley at short range. Every bullet struck down its man. Walker at the same time turned and delivered an equally well-aimed fire, which put the enemy to full flight. The two detachments then passed unmolested through the further defile before the astonished natives could be rallied to the charge. No bribes of _aguardiente_, with which the Mexicans were wont to ply their Indian allies could thenceforth induce the natives to face the deadly American rifles. They hung upon the line of march like coyotes, prowling about the late scene of each encampment, and robbing each new-made grave of its tenant's blanket, the only shroud of the poor filibuster who fell in the waste places of Sonora.