During this advance of the French Skirmishers against the extreme Right of the Allied Front Line, the troops which formed their Support attempted again to force open the rear Gate of Hougomont. The individuals before mentioned as having closed the Gate, were, at the time, occupied in rendering it more secure by placing against it some pieces of ash timber that lay in the yard. The French failing in their endeavours to push in the Gate, a brave Grenadier volunteered to climb over and open it from the inside. Captain WYNDHAM, on perceiving the latter at the top of the gate, instantly desired Sergeant GRAHAM, whose musket he was holding whilst the latter was bringing forward another piece of timber, to drop the wood, take his firelock, and shoot the intruder. The Order was instantly obeyed; and the intrepid assailant, who, for any useful result, ought to have been accompanied by a score of his comrades, fell beneath GRAHAM's deadly aim. It was at this moment that the French Skirmishers who had advanced against the main position, were falling back upon their Support; and the whole of these troops were driven off by the advance of the four Companies of the Coldstream Guards, detached from the main position, as previously described. In the mean time, the French Infantry in the Wood, finding their advance against the Garden so suddenly checked, endeavoured to turn it by its Left. With this view they were debouching through a large gap in the fence, forming an outlet from the Wood into the Orchard; when Lieutenant Colonel Lord SALTOUN, seizing the favourable opportunity, made a most gallant charge upon the head of the Column with the Light Companies of the First Brigade of Guards, and succeeded in driving the Enemy back into the Wood. Shortly afterwards, a large body of the Enemy's Light Troops began to advance stealthily along the eastern hedge of the Hougomont inclosures, communicating at the same time with the Infantry in the Wood on their Left. This was immediately followed by a direct front attack upon the Orchard; which compelled Lord SALTOUN gradually to withdraw his greatly reduced force, from tree to tree, until he reached the hollow way in rear of that inclosure. The Light Troops in front of ALTEN's Division, having perceived the French creeping along the hedge so as to turn the Left Flank of Hougomont, were on the point of forming to oppose them; but on the latter being pointed out to the Prince of ORANGE, who had just come to the front to make his observations, he coolly remarked:--"No, don't stir--the Duke is sure to see that movement, and will take some step to counteract it." He had scarcely spoken, when two Companies of the 3rd Regiment of British Guards, detached from the Allied Line, were seen advancing along the same hedge, in an opposite direction, to meet them.