The final stage in the development of the Mexican constitution was marked by the conquest of Tlaltelolco by Axayacatl, and the appointment of a governor for this suburb in place of an independent sovereign. The military basis of Mexican hegemony coloured the whole of its domestic economy, and resulted in the formation and rise of a military aristocracy in the hands of which lay practically all the executive offices in the city. As commander-in-chief the king was of course the head of the fighting-men, and in some cases actually took the field himself, immediately after his installation, for instance, in order to procure the necessary sacrificial victims. He was supported by two principal officers, the Tlacatecatl and Tlacochcalcatl (Fig. 17, _a_; p. 113), of whom the latter was a purely military functionary, while the former exercised certain administrative functions also. The same titles were borne by the chief subordinates of each of these respectively. A propitious date was awaited for the proclamation of a campaign, the day 1. itzcuintli being considered especially favourable; the hostile country was explored by spies, called Tequihua, who brought back to the king various maps and other documents containing information likely to prove of use during the operations. War was formally declared by sending weapons, down and chalk, the _insignia_ of sacrifice, to the enemy, and the expedition set forth, on a lucky day such as 1. coatl, in a prescribed order. First marched the priests with the idols of the gods, next the Mexican veterans, followed by the less experienced; following them came the forces of Tezcoco and Tlacopan, and finally the fighting-men of allied provinces. When the forces were drawn up, new fire was made by the priests, and the attack commenced. The actual combat does not seem to have been attended by great slaughter, since the chief object of each individual fighter was not to kill his foe, but to make him prisoner. The first captives were immediately handed over to the priests and sacrificed on the spot, while those taken subsequently were carried back to the city. The ceremonial nature of war is clearly shown in the fact that rewards were conferred upon those who succeeded in capturing prisoners, in proportion to the number of their captives, but no account was taken of those who merely slew their opponents. To this fact the Spanish conquerors owed a large measure of their success, since the foe were chiefly anxious to take them alive, and rather avoided inflicting mortal injuries than otherwise. Diaz comments upon the rapidity with which the Tlaxcalans removed their wounded from the scene of action, but without understanding that the reason was to prevent them from falling alive into the hands of the enemy. The Tarascan customs were similar; in time of war the priests offered herbs and tobacco at midnight, selecting a date when the position of the stars was