The Prussian Vth Corps, it was true, stood right on the flank of such an advance across the Seine; its outposts had several times been seen in Rueil. As a preliminary step, General Ducrot undertook to force back this body with 10,000 men and 120 field-guns. Then an intrenched line from Valerien to Carrieres would close the peninsula against interference from the southward. Perhaps, in the face of much-dreaded "public opinion" and the growing restlessness of political parties in Paris, it was more the urgency to be doing something than any serious hope of success which gave rise to such far-reaching schemes. Considerable difficulties had to be met in attacking the enemy's lines, and greater must inevitably arise if the attack should succeed. It was vain to think of bringing through the miles-long trains which are indispensable for victualling an army. Serious embarrassment would ensue when the troops had consumed the three days' rations they would carry with them. To live on the country the army must disperse itself; but with the enemy at its heels close concentration was indispensable. And, in any case, it is hard to see what would have been gained by withdrawing from Paris the forces which had been assembled for the defence of the capital. Success could only have been hoped for if an army from without had been so near as to be able immediately to give the hand to the troops marching out. However, on the 21st of October, after Mont Valerien had all the morning kept up a seemingly ineffective fire, General Ducrot advanced at about one o'clock to attack the position of the Prussian 19th Brigade whose supports held the line Bougival--Jonchere--Fohlenkoppel. Fourteen French field-batteries deployed on either side of Rueil and about the southern base of Valerien; the infantry advanced in five columns behind this artillery front. On the German side only two batteries could at first engage in the unequal duel, and one of these near the Villa Metternich had very soon to retire. The French guns advanced rightward to within 1400 paces of Bougival, and at three o'clock four companies of Zouaves rushed out of Rueil. Being received with a hot fire, they wheeled into the park of Malmaison, and without opposition seized the Chateau of Buzanval and the eastern slope of the deep-cut ravine of Cucufa. And here one of their batteries was brought up into the fighting-line to support them.