And once more, in spring before the season of arms, all the belongings of the host were subjected to some process of the same kind. I have alluded to this in my lecture on the calendar, and need not now reproduce the evidence of the Equirria at the end of February and on March 14, or of the Quinquatrus on March 19, when the _lustratio_ took place of the shields (_ancilia_) of the Salii, the war-priests of Mars, and the Tubilustrium on March 23, which tells its own tale.[456] But I may recall the fact that the calendar supplies us also with evidence that on the return of the host to their own territory all these lustrations had to be repeated in order to rid men, horses, arms, and trumpets of such evil contagion as they might have contracted during their absence. It may be that one special object of lustration after the return of an army was to rid it, with all belonging to it, of the taint of bloodshed, just as the Jewish warriors and their captives were purified before re-entering the camp.[457] But in the Roman pontifical law this idea is hardly discernible, and the only trace I can find of it is a statement of Festus that the soldiers who followed the general's car in a triumph wore laurel wreaths "ut quasi purgati a caede humana intrarent urbem."[458] I may add here that the passage of a triumphing army through the Porta triumphalis, which was probably an isolated arch in the Campus Martius just outside the city wall,[459] most likely had as its original meaning the separation of the host from the profane world in which it had been moving; and the triumphal arches of later times, which were within the city, were thus developed architecturally from an origin which belongs to the region of magic.[460] To the same class of ideas, if I am not much mistaken, belongs the familiar Italian practice of compelling a surrendered army to pass under the yoke. As Livy explains this when he first mentions it, it was symbolical of subjection: "ut exprimatur confessio subactam domitamque esse gentem";[461] and this was no doubt the idea in the minds of the historical Romans. But it may well have been that it had its root in a process which was supposed to deprive the conquered enemy of all dangerous contagion--to separate them from their own land and people before they came into peaceful contact with their conquerors.