The Battle of Waterloo was not begun until about twelve o'clock, because of the state of the ground, which did not admit of the action of cavalry and artillery until several hours had been allowed for its hardening. That inevitable delay was the occasion of the victory of the Allies; for, if the battle had been opened at seven o'clock, the French would have defeated Wellington's army before a Prussian regiment could have arrived on the field. It has been said that the rain was as baneful to the Allies as to the French, as it prevented the early arrival of the Prussians; but the remark comes only from persons who are not familiar with the details of the most momentous of modern pitched battles. Bülow's Prussian corps, which was the first to reach the field, marched through Wavre in the forenoon of the 18th; but no sooner had its advanced guard--an infantry brigade, a cavalry regiment, and one battery--cleared that town, than a fire broke out there, which greatly delayed the march of the remainder of the corps. There were many ammunition-wagons in the streets, and, fearful of losing them, and of being deprived of the means of fighting, the Prussians halted, and turned firemen for the occasion. This not only prevented most of the corps from arriving early on the right flank of the French, but it prevented the advanced guard from acting, Bülow being too good a soldier to risk so small a force as that immediately at his command in an attack on the French army. It was not until about half-past one that the Prussians were first seen by the Emperor, and then at so great a distance that even with glasses it was difficult to say whether the objects looked at were men or trees. But for the bad weather, it is possible that Bülow's whole corps, supposing there had been no fire at Wavre, might have arrived within striking distance of the French army by two o'clock, P.M.; but by that hour the battle between Napoleon and Wellington would have been decided, and the Prussians would have come up only to "augment the slaughter," had the ground been hard enough for operations at an early hour of the day. As the battle was necessarily fought in the afternoon, because of the softness of the soil consequent on the heavy rains of the preceding day and night, there was time gained for the arrival of Bülow's corps by four o'clock of the afternoon of the 18th. Against that corps Napoleon had to send almost twenty thousand of his men, and sixty-six pieces of cannon, all of which might have been employed against Wellington's army, had the battle been fought in the forenoon. As it was, that large force never fired a shot at the English. The other Prussian corps that reached the field toward the close of the day, Zieten's and Pirch's, did not leave Wavre until about noon. The coming up of the advanced guard of Zieten, but a short time before the close of the battle, enabled Wellington to employ the fresh cavalry of