It may be premised that, at Waterloo, Vivian commanded the 6th Brigade of Cavalry of the British and King's German Legion. It was composed of the 1st, 10th, and 18th Hussars, numbering, according to Siborne, 1,279 sabres. They were at first stationed on the _extreme left_ of the first or main portion of the British line. The 10th and 18th regiments were in line in rear of the road to Wavre, and withdrawn a little from the crest of the ridge, the right of the 10th resting upon a lane. The 1st Hussars were also in line, and formed the reserve. The extreme left of this brigade was completely _en l'air_ (_i.e._, unsupported), upon high, open, and flat ground. A piquet, consisting of a squadron of the 10th, occupied the village of Smohain, and their vedettes were within half-carbine-shot of some of the French cavalry. Vandeleur's brigade of light horse was on Vivian's right. But the frequent and furious charges of the enemy made it necessary, as the anxious, bloody day wore on, to strengthen the Duke's left centre; and accordingly in the sheet of Siborne's Atlas representing the field at a quarter before eight p.m., when the Prussians had begun to arrive, Vivian's cavalry appear as then occupying the _middle_ of the much-weakened British force, close at the rear of the Brunswickers and Nassauers. This change of position was effected on Vivian's own responsibility, and to the great satisfaction of the Duke; for when these fresh troops took up their position, the British cavalry had been reduced to mere skeletons of regiments. It is not difficult to fancy how long the day must have seemed to the fiery Hussars, who had not yet struck one blow, and who were anxiously longing for the opportunity of displaying their own valour, and of avenging the deaths of their slain comrades. They were not to wait much longer, as we shall presently see; for, twenty minutes later, Vivian, instead of being at the rear of the British army, was at its head, sabring the Imperial Guard:--'Oh the wild charge they made!' It must be borne in mind that the crisis of the battle had arrived; and Napoleon, like a desperate gambler, had risked his all by sending his masses of reserves against the attenuated British regiments, with instructions, _at all hazards_, to force the centre, in the rear of which Vivian had placed himself, in a most trying position for cavalry, exposed as they were to the fire of the French tirailleurs. His first impression, on contemplating the destruction which he saw around him, was that he had come, once more, to cover a retreat of the Anglo-allied army: and, indeed, but for the exertions of himself and others--actually using the flats of their sabres--the contemptible Dutch-Belgian troops, who formed Wellington's second line, would have probably fled from the field, and have left a hideous and fatal gap in the British line.