At length, the Support so greatly needed by PONSONBY's Brigade arrived upon its Left Flank. VANDELEUR, having passed the hollow way and ravine which intercepted his progress towards the scene of action, had reached that part of the crest of the position occupied by BEST's Hanoverian Brigade, through which it now advanced to the front in Open Column of divisions. The 12th Light Dragoons, being the leading Regiment, moved quickly down the slope: the 16th Regiment remained higher up the acclivity; while the 11th were drawn up in reserve upon the brow of the hill. The 12th and 16th wheeled into Line to their right. Lieutenant Colonel the Hon. FREDERICK PONSONBY, who commanded the 12th, perceiving the confusion that prevailed amidst the French Infantry in the valley, as also the extremely critical situation of a great number of scattered red coated Dragoons nearly on the crest of the French position, instantly charged a mass of unsteady Infantry which intervened between him and these Dragoons. This Infantry comprised the rearmost supporting Column of MARCOGNET's Division, and was the only one of the attacking Columns yet intact. It was now destined to share their fate. Already alarmed by the disorder into which the entire of the Infantry on its left had been thrown, and now attacked so suddenly and unexpectedly on its right, it was penetrated by the charge of the 12th. These Dragoons having forced their way through the Column, whereby their order was naturally much broken, came upon the Right Flank of the Lancers who were in pursuit of PONSONBY's Brigade. Quickening their speed, they dashed in amongst the French Cavalry, and acting almost perpendicularly upon their Flank, they "rolled up" such as were immediately in their front. The 16th Light Dragoons, with VANDELEUR at their head, very gallantly charged obliquely upon the front of the Lancers, whose further advance was completely checked by this double attack. On their extreme Right, the 16th rather clashed with some of the retiring Dragoons: but the two Regiments, carrying every thing before them, succeeded in driving the French Light Cavalry down again to the foot of the valley; which they had been ordered, previously to their charge, not to pass. Some few of both the 12th and 16th did, nevertheless, madly rush up the opposite Height; where, by this time, fresh troops had arrived, who made them suffer for their temerity.